77864639 has 4 divisors (see below), whose sum is σ = 78199056. Its totient is φ = 77530224.

The previous prime is 77864627. The next prime is 77864651. The reversal of 77864639 is 93646877.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (77864627) and next prime (77864651).

It is a cyclic number.

It is not a de Polignac number, because 77864639 - 2²⁰ = 76816063 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77864659) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166859 + ... + 167324.

It is an arithmetic number, because the mean of its divisors is an integer number (19549764).

Almost surely, 2^77864639 is an apocalyptic number.

77864639 is a deficient number, since it is larger than the sum of its proper divisors (334417).

77864639 is a wasteful number, since it uses less digits than its factorization.

77864639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334416.

The product of its digits is 1524096, while the sum is 50.

The square root of 77864639 is about 8824.0942311378. The cubic root of 77864639 is about 427.0185663616.

The spelling of 77864639 in words is "seventy-seven million, eight hundred sixty-four thousand, six hundred thirty-nine".