21591172590 has 64 divisors (see below), whose sum is σ = 55912514112. Its totient is φ = 5304499200.

The previous prime is 21591172583. The next prime is 21591172601. The reversal of 21591172590 is 9527119512.

It is a super-2 number, since 2×21591172590² (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 31 ways as a sum of consecutive naturals, for example, 150060 + ... + 256320.

It is an arithmetic number, because the mean of its divisors is an integer number (873633033).

Almost surely, 2^21591172590 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21591172590, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27956257056).

21591172590 is an abundant number, since it is smaller than the sum of its proper divisors (34321341522).

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

21591172590 is a wasteful number, since it uses less digits than its factorization.

21591172590 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106805.

The product of its (nonzero) digits is 56700, while the sum is 42.

The spelling of 21591172590 in words is "twenty-one billion, five hundred ninety-one million, one hundred seventy-two thousand, five hundred ninety".