21721871835522 has 16 divisors (see below), whose sum is σ = 48270826301280. Its totient is φ = 7240623945156.

The previous prime is 21721871835479. The next prime is 21721871835527. The reversal of 21721871835522 is 22553817812712.

21721871835522 is a `hidden beast` number, since 2 + 1 + 7 + 2 + 1 + 8 + 7 + 1 + 83 + 552 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54), and also a Moran number because the ratio is a prime number: 402256885843 = 21721871835522 / (2 + 1 + 7 + 2 + 1 + 8 + 7 + 1 + 8 + 3 + 5 + 5 + 2 + 2).

It is not an unprimeable number, because it can be changed into a prime (21721871835527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 201128442868 + ... + 201128442975.

It is an arithmetic number, because the mean of its divisors is an integer number (3016926643830).

Almost surely, 2^{21721871835522} is an apocalyptic number.

21721871835522 is an abundant number, since it is smaller than the sum of its proper divisors (26548954465758).

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

21721871835522 is a wasteful number, since it uses less digits than its factorization.

21721871835522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402256885854 (or 402256885848 counting only the distinct ones).

The product of its digits is 3763200, while the sum is 54.

The spelling of 21721871835522 in words is "twenty-one trillion, seven hundred twenty-one billion, eight hundred seventy-one million, eight hundred thirty-five thousand, five hundred twenty-two".