21655630023621 has 64 divisors (see below), whose sum is σ = 32041154576640. Its totient is φ = 12900077936640.

The previous prime is 21655630023611. The next prime is 21655630023631. The reversal of 21655630023621 is 12632003655612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21655630023611) and next prime (21655630023631).

It is not a de Polignac number, because 21655630023621 - 2¹¹ = 21655630021573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655630023611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1017784635 + ... + 1017805911.

It is an arithmetic number, because the mean of its divisors is an integer number (500643040260).

Almost surely, 2^{21655630023621} is an apocalyptic number.

It is an amenable number.

21655630023621 is a deficient number, since it is larger than the sum of its proper divisors (10385524553019).

21655630023621 is a wasteful number, since it uses less digits than its factorization.

21655630023621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22806.

The product of its (nonzero) digits is 388800, while the sum is 42.

The spelling of 21655630023621 in words is "twenty-one trillion, six hundred fifty-five billion, six hundred thirty million, twenty-three thousand, six hundred twenty-one".