77920865 has 16 divisors (see below), whose sum is σ = 103934016. Its totient is φ = 55598400.

The previous prime is 77920861. The next prime is 77920873. The reversal of 77920865 is 56802977.

It is not a de Polignac number, because 77920865 - 2² = 77920861 is a prime.

It is a super-2 number, since 2×77920865² = 12143322404696450, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77920861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10451 + ... + 16280.

It is an arithmetic number, because the mean of its divisors is an integer number (6495876).

Almost surely, 2^77920865 is an apocalyptic number.

It is an amenable number.

77920865 is a deficient number, since it is larger than the sum of its proper divisors (26013151).

77920865 is a wasteful number, since it uses less digits than its factorization.

77920865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26800.

The product of its (nonzero) digits is 211680, while the sum is 44.

The square root of 77920865 is about 8827.2795922640. The cubic root of 77920865 is about 427.1213248985.

The spelling of 77920865 in words is "seventy-seven million, nine hundred twenty thousand, eight hundred sixty-five".