21501072123564 has 48 divisors (see below), whose sum is σ = 54740406502656. Its totient is φ = 6514237742400.

The previous prime is 21501072123551. The next prime is 21501072123569. The reversal of 21501072123564 is 46532127010512.

It is a super-2 number, since 2×21501072123564² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21501072123569) 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, 14786152 + ... + 16175055.

It is an arithmetic number, because the mean of its divisors is an integer number (1140425135472).

Almost surely, 2^{21501072123564} is an apocalyptic number.

It is an amenable number.

21501072123564 is an abundant number, since it is smaller than the sum of its proper divisors (33239334379092).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21501072123564 is a wasteful number, since it uses less digits than its factorization.

21501072123564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30966486 (or 30966484 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 39.

The spelling of 21501072123564 in words is "twenty-one trillion, five hundred one billion, seventy-two million, one hundred twenty-three thousand, five hundred sixty-four".