78031638 has 24 divisors (see below), whose sum is σ = 170308008. Its totient is φ = 25819872.

The previous prime is 78031621. The next prime is 78031661. The reversal of 78031638 is 83613087.

78031638 = 1687² + 1688² + ... + 1713².

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 13356 + ... + 18287.

It is an arithmetic number, because the mean of its divisors is an integer number (7096167).

Almost surely, 2^78031638 is an apocalyptic number.

78031638 is an abundant number, since it is smaller than the sum of its proper divisors (92276370).

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

78031638 is a wasteful number, since it uses less digits than its factorization.

78031638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31788 (or 31785 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 78031638 is about 8833.5518337756. The cubic root of 78031638 is about 427.3236288974.

The spelling of 78031638 in words is "seventy-eight million, thirty-one thousand, six hundred thirty-eight".