21644668737 has 12 divisors (see below), whose sum is σ = 31302520704. Its totient is φ = 14412241080.

The previous prime is 21644668697. The next prime is 21644668769. The reversal of 21644668737 is 73786644612.

It is not a de Polignac number, because 21644668737 - 2¹⁴ = 21644652353 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21644668337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1453689 + ... + 1468502.

It is an arithmetic number, because the mean of its divisors is an integer number (2608543392).

Almost surely, 2^21644668737 is an apocalyptic number.

It is an amenable number.

21644668737 is a deficient number, since it is larger than the sum of its proper divisors (9657851967).

21644668737 is a wasteful number, since it uses less digits than its factorization.

21644668737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2923020 (or 2923017 counting only the distinct ones).

The product of its digits is 8128512, while the sum is 54.

The spelling of 21644668737 in words is "twenty-one billion, six hundred forty-four million, six hundred sixty-eight thousand, seven hundred thirty-seven".