21685008 has 20 divisors (see below), whose sum is σ = 56019728. Its totient is φ = 7228320.

The previous prime is 21685007. The next prime is 21685049. The reversal of 21685008 is 80058612.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21685007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 225838 + ... + 225933.

Almost surely, 2^21685008 is an apocalyptic number.

It is an amenable number.

21685008 is an abundant number, since it is smaller than the sum of its proper divisors (34334720).

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

21685008 is a wasteful number, since it uses less digits than its factorization.

21685008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451782 (or 451776 counting only the distinct ones).

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

The square root of 21685008 is about 4656.7164397245. The cubic root of 21685008 is about 278.8601963983.

The spelling of 21685008 in words is "twenty-one million, six hundred eighty-five thousand, eight".