642038391 has 6 divisors (see below), whose sum is σ = 927388800. Its totient is φ = 428025588.

The previous prime is 642038363. The next prime is 642038459. The reversal of 642038391 is 193830246.

642038391 is a `hidden beast` number, since 64 + 203 + 8 + 391 = 666.

It is not a de Polignac number, because 642038391 - 2²⁶ = 574929527 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642038321) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35668791 + ... + 35668808.

It is an arithmetic number, because the mean of its divisors is an integer number (154564800).

Almost surely, 2^642038391 is an apocalyptic number.

642038391 is a deficient number, since it is larger than the sum of its proper divisors (285350409).

642038391 is a wasteful number, since it uses less digits than its factorization.

642038391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71337605 (or 71337602 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 642038391 is about 25338.4764932701. The cubic root of 642038391 is about 862.6878189587.

The spelling of 642038391 in words is "six hundred forty-two million, thirty-eight thousand, three hundred ninety-one".