21521252544 has 224 divisors, whose sum is σ = 65989541376. Its totient is φ = 6117703680.

The previous prime is 21521252531. The next prime is 21521252563. The reversal of 21521252544 is 44525212512.

It is a super-2 number, since 2×21521252544² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13391389 + ... + 13392995.

Almost surely, 2^21521252544 is an apocalyptic number.

21521252544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21521252544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32994770688).

21521252544 is an abundant number, since it is smaller than the sum of its proper divisors (44468288832).

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

21521252544 is a wasteful number, since it uses less digits than its factorization.

21521252544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2023 (or 2013 counting only the distinct ones).

The product of its digits is 32000, while the sum is 33.

The spelling of 21521252544 in words is "twenty-one billion, five hundred twenty-one million, two hundred fifty-two thousand, five hundred forty-four".