21210809188 has 24 divisors (see below), whose sum is σ = 37473837408. Its totient is φ = 10504131456.

The previous prime is 21210809173. The next prime is 21210809227. The reversal of 21210809188 is 88190801212.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21210809188.

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, 654495 + ... + 686137.

It is an arithmetic number, because the mean of its divisors is an integer number (1561409892).

Almost surely, 2^21210809188 is an apocalyptic number.

It is an amenable number.

21210809188 is a deficient number, since it is larger than the sum of its proper divisors (16263028220).

21210809188 is a wasteful number, since it uses less digits than its factorization.

21210809188 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33243 (or 33241 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 40.

The spelling of 21210809188 in words is "twenty-one billion, two hundred ten million, eight hundred nine thousand, one hundred eighty-eight".