21534401637 has 16 divisors (see below), whose sum is σ = 36460362880. Its totient is φ = 12305372256.

The previous prime is 21534401633. The next prime is 21534401657. The reversal of 21534401637 is 73610443512.

21534401637 is a `hidden beast` number, since 2 + 1 + 53 + 440 + 163 + 7 = 666.

It is not a de Polignac number, because 21534401637 - 2² = 21534401633 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534401633) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56969128 + ... + 56969505.

It is an arithmetic number, because the mean of its divisors is an integer number (2278772680).

Almost surely, 2^21534401637 is an apocalyptic number.

21534401637 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21534401637 is a deficient number, since it is larger than the sum of its proper divisors (14925961243).

21534401637 is a wasteful number, since it uses less digits than its factorization.

21534401637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113938649 (or 113938643 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21534401637 in words is "twenty-one billion, five hundred thirty-four million, four hundred one thousand, six hundred thirty-seven".