21161791986 has 16 divisors (see below), whose sum is σ = 42345502464. Its totient is φ = 7050277584.

The previous prime is 21161791969. The next prime is 21161792017. The reversal of 21161791986 is 68919716112.

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, 900706 + ... + 923901.

It is an arithmetic number, because the mean of its divisors is an integer number (2646593904).

Almost surely, 2^21161791986 is an apocalyptic number.

21161791986 is an abundant number, since it is smaller than the sum of its proper divisors (21183710478).

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

21161791986 is a wasteful number, since it uses less digits than its factorization.

21161791986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1826545.

The product of its digits is 326592, while the sum is 51.

The spelling of 21161791986 in words is "twenty-one billion, one hundred sixty-one million, seven hundred ninety-one thousand, nine hundred eighty-six".