21506205451220 has 48 divisors (see below), whose sum is σ = 52147005415680. Its totient is φ = 7297540107264.

The previous prime is 21506205451219. The next prime is 21506205451261. The reversal of 21506205451220 is 2215450260512.

It is a Harshad number since it is a multiple of its sum of digits (35).

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, 791820200 + ... + 791847359.

It is an arithmetic number, because the mean of its divisors is an integer number (1086395946160).

Almost surely, 2^{21506205451220} is an apocalyptic number.

21506205451220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21506205451220 is an abundant number, since it is smaller than the sum of its proper divisors (30640799964460).

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

21506205451220 is a wasteful number, since it uses less digits than its factorization.

21506205451220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1583667672 (or 1583667670 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 35.

The spelling of 21506205451220 in words is "twenty-one trillion, five hundred six billion, two hundred five million, four hundred fifty-one thousand, two hundred twenty".