21506205472540 has 48 divisors (see below), whose sum is σ = 45208503885888. Its totient is φ = 8593823960064.

The previous prime is 21506205472537. The next prime is 21506205472627. The reversal of 21506205472540 is 4527450260512.

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, 111257814 + ... + 111450946.

It is an arithmetic number, because the mean of its divisors is an integer number (941843830956).

Almost surely, 2^{21506205472540} is an apocalyptic number.

21506205472540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21506205472540 is an abundant number, since it is smaller than the sum of its proper divisors (23702298413348).

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

21506205472540 is a wasteful number, since it uses less digits than its factorization.

21506205472540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198718 (or 198716 counting only the distinct ones).

The product of its (nonzero) digits is 672000, while the sum is 43.

The spelling of 21506205472540 in words is "twenty-one trillion, five hundred six billion, two hundred five million, four hundred seventy-two thousand, five hundred forty".