21891992706 has 12 divisors (see below), whose sum is σ = 47432650902. Its totient is φ = 7297330896.

The previous prime is 21891992699. The next prime is 21891992719. The reversal of 21891992706 is 60729919812.

21891992706 is a `hidden beast` number, since 2 + 189 + 199 + 270 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 14691621681 + 7200371025 = 121209^2 + 84855^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 608110891 + ... + 608110926.

Almost surely, 2^21891992706 is an apocalyptic number.

21891992706 is an abundant number, since it is smaller than the sum of its proper divisors (25540658196).

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

21891992706 is a wasteful number, since it uses less digits than its factorization.

21891992706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1216221825 (or 1216221822 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The spelling of 21891992706 in words is "twenty-one billion, eight hundred ninety-one million, nine hundred ninety-two thousand, seven hundred six".