21644581460 has 48 divisors (see below), whose sum is σ = 46257547392. Its totient is φ = 8505571200.

The previous prime is 21644581451. The next prime is 21644581471. The reversal of 21644581460 is 6418544612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 374930 + ... + 428790.

It is an arithmetic number, because the mean of its divisors is an integer number (963698904).

Almost surely, 2^21644581460 is an apocalyptic number.

21644581460 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21644581460 is an abundant number, since it is smaller than the sum of its proper divisors (24612965932).

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

21644581460 is a wasteful number, since it uses less digits than its factorization.

21644581460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54224 (or 54222 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 41.

The spelling of 21644581460 in words is "twenty-one billion, six hundred forty-four million, five hundred eighty-one thousand, four hundred sixty".