77811681 has 16 divisors (see below), whose sum is σ = 104924160. Its totient is φ = 51290880.

The previous prime is 77811653. The next prime is 77811683. The reversal of 77811681 is 18611877.

It is not a de Polignac number, because 77811681 - 2¹⁹ = 77287393 is a prime.

It is a super-2 number, since 2×77811681² = 12109315400091522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (77811683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 130921 + ... + 131513.

It is an arithmetic number, because the mean of its divisors is an integer number (6557760).

Almost surely, 2^77811681 is an apocalyptic number.

It is an amenable number.

77811681 is a deficient number, since it is larger than the sum of its proper divisors (27112479).

77811681 is a wasteful number, since it uses less digits than its factorization.

77811681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1016.

The product of its digits is 18816, while the sum is 39.

The square root of 77811681 is about 8821.0929594920. The cubic root of 77811681 is about 426.9217351671.

The spelling of 77811681 in words is "seventy-seven million, eight hundred eleven thousand, six hundred eighty-one".