642525921 has 12 divisors (see below), whose sum is σ = 928362448. Its totient is φ = 428226264.

The previous prime is 642525911. The next prime is 642525937. The reversal of 642525921 is 129525246.

642525921 is a `hidden beast` number, since 6 + 42 + 525 + 92 + 1 = 666.

It is not a de Polignac number, because 642525921 - 2⁶ = 642525857 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (642525911) by changing a digit.

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, 31086 + ... + 47448.

Almost surely, 2^642525921 is an apocalyptic number.

It is an amenable number.

642525921 is a deficient number, since it is larger than the sum of its proper divisors (285836527).

642525921 is a wasteful number, since it uses less digits than its factorization.

642525921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20732 (or 20729 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 642525921 is about 25348.0950171803. The cubic root of 642525921 is about 862.9061235473.

The spelling of 642525921 in words is "six hundred forty-two million, five hundred twenty-five thousand, nine hundred twenty-one".