78639775 has 12 divisors (see below), whose sum is σ = 97830792. Its totient is φ = 62707040.

The previous prime is 78639767. The next prime is 78639787. The reversal of 78639775 is 57793687.

It is a happy number.

It is not a de Polignac number, because 78639775 - 2³ = 78639767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2964 + ... + 12886.

It is an arithmetic number, because the mean of its divisors is an integer number (8152566).

Almost surely, 2^78639775 is an apocalyptic number.

78639775 is a deficient number, since it is larger than the sum of its proper divisors (19191017).

78639775 is a wasteful number, since it uses less digits than its factorization.

78639775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10250 (or 10245 counting only the distinct ones).

The product of its digits is 2222640, while the sum is 52.

The square root of 78639775 is about 8867.9070247720. The cubic root of 78639775 is about 428.4308683229.

The spelling of 78639775 in words is "seventy-eight million, six hundred thirty-nine thousand, seven hundred seventy-five".