21145165928 has 8 divisors (see below), whose sum is σ = 39647186130. Its totient is φ = 10572582960.

The previous prime is 21145165889. The next prime is 21145165957. The reversal of 21145165928 is 82956154112.

It can be written as a sum of positive squares in only one way, i.e., 11638525924 + 9506640004 = 107882^2 + 97502^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1321572863 + ... + 1321572878.

Almost surely, 2^21145165928 is an apocalyptic number.

It is an amenable number.

21145165928 is a deficient number, since it is larger than the sum of its proper divisors (18502020202).

21145165928 is a wasteful number, since it uses less digits than its factorization.

21145165928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2643145747 (or 2643145743 counting only the distinct ones).

The product of its digits is 172800, while the sum is 44.

The spelling of 21145165928 in words is "twenty-one billion, one hundred forty-five million, one hundred sixty-five thousand, nine hundred twenty-eight".