21521666008 has 32 divisors (see below), whose sum is σ = 41323176000. Its totient is φ = 10505214720.

The previous prime is 21521665943. The next prime is 21521666011. The reversal of 21521666008 is 80066612512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135063 + ... + 247558.

It is an arithmetic number, because the mean of its divisors is an integer number (1291349250).

Almost surely, 2^21521666008 is an apocalyptic number.

It is an amenable number.

21521666008 is a deficient number, since it is larger than the sum of its proper divisors (19801509992).

21521666008 is a wasteful number, since it uses less digits than its factorization.

21521666008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382795 (or 382791 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 37.

The spelling of 21521666008 in words is "twenty-one billion, five hundred twenty-one million, six hundred sixty-six thousand, eight".