77921865 has 32 divisors (see below), whose sum is σ = 158319360. Its totient is φ = 35620992.

The previous prime is 77921843. The next prime is 77921873. The reversal of 77921865 is 56812977.

It is not a de Polignac number, because 77921865 - 2¹⁰ = 77920841 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 77921865.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40284 + ... + 42173.

It is an arithmetic number, because the mean of its divisors is an integer number (4947480).

Almost surely, 2^77921865 is an apocalyptic number.

It is an amenable number.

77921865 is an abundant number, since it is smaller than the sum of its proper divisors (80397495).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77921865 is a wasteful number, since it uses less digits than its factorization.

77921865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82478 (or 82472 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 77921865 is about 8827.3362346746. The cubic root of 77921865 is about 427.1231520492.

The spelling of 77921865 in words is "seventy-seven million, nine hundred twenty-one thousand, eight hundred sixty-five".