21865008 has 40 divisors (see below), whose sum is σ = 61621056. Its totient is φ = 6625600.

The previous prime is 21865007. The next prime is 21865037. The reversal of 21865008 is 80056812.

It is not an unprimeable number, because it can be changed into a prime (21865001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20178 + ... + 21233.

Almost surely, 2^21865008 is an apocalyptic number.

It is an amenable number.

21865008 is an abundant number, since it is smaller than the sum of its proper divisors (39756048).

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

21865008 is a wasteful number, since it uses less digits than its factorization.

21865008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41433 (or 41427 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 21865008 is about 4676.0034217267. The cubic root of 21865008 is about 279.6296464069.

The spelling of 21865008 in words is "twenty-one million, eight hundred sixty-five thousand, eight".