21433568645 has 18 divisors (see below), whose sum is σ = 25923396534. Its totient is φ = 17012504320.

The previous prime is 21433568633. The next prime is 21433568699. The reversal of 21433568645 is 54686533412.

It can be written as a sum of positive squares in 9 ways, for example, as 6872078404 + 14561490241 = 82898^2 + 120671^2 .

It is not a de Polignac number, because 21433568645 - 2⁸ = 21433568389 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21433568645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 76275905 + ... + 76276185.

Almost surely, 2^21433568645 is an apocalyptic number.

It is an amenable number.

21433568645 is a deficient number, since it is larger than the sum of its proper divisors (4489827889).

21433568645 is an frugal number, since it uses more digits than its factorization.

21433568645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1033 (or 519 counting only the distinct ones).

The product of its digits is 2073600, while the sum is 47.

The spelling of 21433568645 in words is "twenty-one billion, four hundred thirty-three million, five hundred sixty-eight thousand, six hundred forty-five".