21644131505655 has 32 divisors (see below), whose sum is σ = 37850534350848. Its totient is φ = 10514037312000.

The previous prime is 21644131505651. The next prime is 21644131505657. The reversal of 21644131505655 is 55650513144612.

It is not a de Polignac number, because 21644131505655 - 2² = 21644131505651 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21644131505651) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1369007371 + ... + 1369023180.

It is an arithmetic number, because the mean of its divisors is an integer number (1182829198464).

Almost surely, 2^{21644131505655} is an apocalyptic number.

21644131505655 is a deficient number, since it is larger than the sum of its proper divisors (16206402845193).

21644131505655 is a wasteful number, since it uses less digits than its factorization.

21644131505655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2738030607.

The product of its (nonzero) digits is 2160000, while the sum is 48.

The spelling of 21644131505655 in words is "twenty-one trillion, six hundred forty-four billion, one hundred thirty-one million, five hundred five thousand, six hundred fifty-five".