21231515025 has 108 divisors (see below), whose sum is σ = 44345515500. Its totient is φ = 9681960960.

The previous prime is 21231515023. The next prime is 21231515029. The reversal of 21231515025 is 52051513212.

21231515025 is a `hidden beast` number, since 2 + 1 + 2 + 3 + 151 + 502 + 5 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 713530944 + 20517984081 = 26712^2 + 143241^2 .

It is not a de Polignac number, because 21231515025 - 2¹ = 21231515023 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21231515025.

It is not an unprimeable number, because it can be changed into a prime (21231515023) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 4948081 + ... + 4952369.

It is an arithmetic number, because the mean of its divisors is an integer number (410606625).

Almost surely, 2^21231515025 is an apocalyptic number.

21231515025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21231515025 is an abundant number, since it is smaller than the sum of its proper divisors (23114000475).

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

21231515025 is a wasteful number, since it uses less digits than its factorization.

21231515025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4768 (or 4753 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The spelling of 21231515025 in words is "twenty-one billion, two hundred thirty-one million, five hundred fifteen thousand, twenty-five".