77681 has 2 divisors, whose sum is σ = 77682. Its totient is φ = 77680.

The previous prime is 77659. The next prime is 77687. The reversal of 77681 is 18677.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58081 + 19600 = 241^2 + 140^2 .

It is a cyclic number.

It is not a de Polignac number, because 77681 - 2⁶ = 77617 is a prime.

It is a super-2 number, since 2×77681² = 12068675522, which contains 22 as substring.

It is a Chen prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (77687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38840 + 38841.

It is an arithmetic number, because the mean of its divisors is an integer number (38841).

2⁷⁷⁶⁸¹ is an apocalyptic number.

It is an amenable number.

77681 is a deficient number, since it is larger than the sum of its proper divisors (1).

77681 is an equidigital number, since it uses as much as digits as its factorization.

77681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2352, while the sum is 29.

The square root of 77681 is about 278.7131141515. The cubic root of 77681 is about 42.6682603029.

The spelling of 77681 in words is "seventy-seven thousand, six hundred eighty-one".