21506212165600 has 144 divisors (see below), whose sum is σ = 52881072426000. Its totient is φ = 8540438650880.

The previous prime is 21506212165597. The next prime is 21506212165621. The reversal of 21506212165600 is 656121260512.

It is a self number, because there is not a number n which added to its sum of digits gives 21506212165600.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 241573896 + ... + 241662904.

It is an arithmetic number, because the mean of its divisors is an integer number (367229669625).

Almost surely, 2^{21506212165600} is an apocalyptic number.

21506212165600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21506212165600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26440536213000).

21506212165600 is an abundant number, since it is smaller than the sum of its proper divisors (31374860260400).

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

21506212165600 is a wasteful number, since it uses less digits than its factorization.

21506212165600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91205 (or 91192 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21506212165600 in words is "twenty-one trillion, five hundred six billion, two hundred twelve million, one hundred sixty-five thousand, six hundred".