21163523764 has 6 divisors (see below), whose sum is σ = 37036166594. Its totient is φ = 10581761880.

The previous prime is 21163523741. The next prime is 21163523779. The reversal of 21163523764 is 46732536112.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20767115664 + 396408100 = 144108^2 + 19910^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2645440467 + ... + 2645440474.

Almost surely, 2^21163523764 is an apocalyptic number.

It is an amenable number.

21163523764 is a deficient number, since it is larger than the sum of its proper divisors (15872642830).

21163523764 is a wasteful number, since it uses less digits than its factorization.

21163523764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5290880945 (or 5290880943 counting only the distinct ones).

The product of its digits is 181440, while the sum is 40.

The spelling of 21163523764 in words is "twenty-one billion, one hundred sixty-three million, five hundred twenty-three thousand, seven hundred sixty-four".