21504404540 has 48 divisors (see below), whose sum is σ = 45595533312. Its totient is φ = 8518902336.

The previous prime is 21504404521. The next prime is 21504404557. The reversal of 21504404540 is 4540440512.

It is a super-2 number, since 2×21504404540² (a number of 21 digits) contains 22 as substring.

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, 1483769 + ... + 1498191.

It is an arithmetic number, because the mean of its divisors is an integer number (949906944).

Almost surely, 2^21504404540 is an apocalyptic number.

21504404540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21504404540 is an abundant number, since it is smaller than the sum of its proper divisors (24091128772).

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

21504404540 is a wasteful number, since it uses less digits than its factorization.

21504404540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15146 (or 15144 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 29.

The spelling of 21504404540 in words is "twenty-one billion, five hundred four million, four hundred four thousand, five hundred forty".