77 (seventy-seven) is the
natural number
In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...
following
76 and preceding
78. Seventy-seven is the smallest positive integer requiring five syllables in
English.
In mathematics
77 is:
*the 22nd discrete
semiprime and the first of the (7.q) family, where q is a higher prime.
* with a prime
aliquot sum
In number theory, the aliquot sum of a positive integer is the sum of all proper divisors of , that is, all divisors of other than itself.
That is,
s(n)=\sum_ d \, .
It can be used to characterize the prime numbers, perfect numbers, sociabl ...
of
19 within an
aliquot sequence
In mathematics, an aliquot sequence is a sequence of positive integers in which each term is the sum of the proper divisors of the previous term. If the sequence reaches the number 1, it ends, since the sum of the proper divisors of 1 is 0.
Def ...
(77,
19,
1, 0) to the Prime in the
19-aliquot tree. 77 is the second composite member of the
19-aliquot tree with
65
*a
Blum integer since both 7 and 11 are
Gaussian primes.
*the sum of three consecutive squares, 4
2 + 5
2 + 6
2.
*the sum of the first eight
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a Product (mathematics), product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime ...
s.
*the number of
integer partition
In number theory and combinatorics, a partition of a non-negative integer , also called an integer partition, is a way of writing as a summation, sum of positive integers. Two sums that differ only in the order of their summands are considered ...
s of the number 12.
* the largest number that cannot be written as a sum of distinct numbers whose reciprocals sum to 1.
*the number of digits of the 12th
perfect number
In number theory, a perfect number is a positive integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number itself. For instance, 6 has proper divisors 1, 2 and 3, and 1 + 2 + 3 = 6, so 6 is a perfec ...
.
It is possible for a
sudoku puzzle to have as many as 77 givens, yet lack a unique solution.
It and 49 are the only 2-digit numbers whose
home primes (in base 10) have not been calculated.
In history
During
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
in
Sweden
Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
at the border with
Norway
Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
, "77" was used as a
shibboleth
A shibboleth ( ; ) is any custom or tradition—usually a choice of phrasing or single word—that distinguishes one group of people from another. Historically, shibboleths have been used as passwords, ways of self-identification, signals of l ...
(
password
A password, sometimes called a passcode, is secret data, typically a string of characters, usually used to confirm a user's identity. Traditionally, passwords were expected to be memorized, but the large number of password-protected services t ...
), because the tricky pronunciation in Swedish made it easy to instantly discern whether the speaker was native
Swedish,
Norwegian, or
German.
In religion
In the
Islam
Islam is an Abrahamic religions, Abrahamic monotheistic religion based on the Quran, and the teachings of Muhammad. Adherents of Islam are called Muslims, who are estimated to number Islam by country, 2 billion worldwide and are the world ...
ic tradition, "77" figures prominently.
Muhammad
Muhammad (8 June 632 CE) was an Arab religious and political leader and the founder of Islam. Muhammad in Islam, According to Islam, he was a prophet who was divinely inspired to preach and confirm the tawhid, monotheistic teachings of A ...
is reported to have explained, "Faith has sixty-odd, or seventy-odd branches, the highest and best of which is to declare and believe that there is no god but Allah without any equals or highers and anyone worthy of worship, and the lowest of which is to remove something harmful from a road. Shyness, too, is a branch of faith." While some scholars refrain from clarifying "sixty-odd or seventy-odd", various numbers have been suggested, 77 being the most common.
Some have gone so far as to delineate these branches.
In religious numerology
In certain numerological systems based on the English alphabet, the number 77 is associated with
Jesus Christ
Jesus (AD 30 or 33), also referred to as Jesus Christ, Jesus of Nazareth, and many Names and titles of Jesus in the New Testament, other names and titles, was a 1st-century Jewish preacher and religious leader. He is the Jesus in Chris ...
. CHRIST is C = 3, H = 8, R = 18, I = 9, S = 19, T = 20, which added together equal 77.
In other fields
Seventy-seven is also:
* 10-77, the New York City Fire Department's (FDNY)
10 code for high-rise, multiple-dwelling fire
References
External links
{{DEFAULTSORT:77 (Number)
Integers