21557224544 has 72 divisors (see below), whose sum is σ = 45916317720. Its totient is φ = 9928180736.

The previous prime is 21557224543. The next prime is 21557224547. The reversal of 21557224544 is 44542275512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21557224543) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1192727 + ... + 1210665.

It is an arithmetic number, because the mean of its divisors is an integer number (637726635).

Almost surely, 2^21557224544 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21557224544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22958158860).

21557224544 is an abundant number, since it is smaller than the sum of its proper divisors (24359093176).

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

21557224544 is a wasteful number, since it uses less digits than its factorization.

21557224544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18060 (or 18005 counting only the distinct ones).

The product of its digits is 448000, while the sum is 41.

The spelling of 21557224544 in words is "twenty-one billion, five hundred fifty-seven million, two hundred twenty-four thousand, five hundred forty-four".