18921621892 has 12 divisors (see below), whose sum is σ = 33116518540. Its totient is φ = 9459759456.

The previous prime is 18921621841. The next prime is 18921621937. The reversal of 18921621892 is 29812612981.

It can be written as a sum of positive squares in 2 ways, for example, as 11639388996 + 7282232896 = 107886^2 + 85336^2 .

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, 221667 + ... + 294922.

Almost surely, 2^18921621892 is an apocalyptic number.

It is an amenable number.

18921621892 is a deficient number, since it is larger than the sum of its proper divisors (14194896648).

18921621892 is a wasteful number, since it uses less digits than its factorization.

18921621892 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525750 (or 525748 counting only the distinct ones).

The product of its digits is 248832, while the sum is 49.

The spelling of 18921621892 in words is "eighteen billion, nine hundred twenty-one million, six hundred twenty-one thousand, eight hundred ninety-two".