21191909136 has 20 divisors (see below), whose sum is σ = 54745765392. Its totient is φ = 7063969696.

The previous prime is 21191909087. The next prime is 21191909191. The reversal of 21191909136 is 63190919112.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220749006 + ... + 220749101.

Almost surely, 2^21191909136 is an apocalyptic number.

It is an amenable number.

21191909136 is an abundant number, since it is smaller than the sum of its proper divisors (33553856256).

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

21191909136 is a wasteful number, since it uses less digits than its factorization.

21191909136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441498118 (or 441498112 counting only the distinct ones).

The product of its (nonzero) digits is 26244, while the sum is 42.

The spelling of 21191909136 in words is "twenty-one billion, one hundred ninety-one million, nine hundred nine thousand, one hundred thirty-six".