21315010525 has 6 divisors (see below), whose sum is σ = 26430613082. Its totient is φ = 17052008400.

The previous prime is 21315010523. The next prime is 21315010699. The reversal of 21315010525 is 52501051312.

It can be written as a sum of positive squares in 3 ways, for example, as 118853604 + 21196156921 = 10902^2 + 145589^2 .

It is not a de Polignac number, because 21315010525 - 2¹ = 21315010523 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 852600421 = 21315010525 / (2 + 1 + 3 + 1 + 5 + 0 + 1 + 0 + 5 + 2 + 5).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21315010525.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315010523) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 426300186 + ... + 426300235.

Almost surely, 2^21315010525 is an apocalyptic number.

21315010525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21315010525 is a deficient number, since it is larger than the sum of its proper divisors (5115602557).

21315010525 is an equidigital number, since it uses as much as digits as its factorization.

21315010525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852600431 (or 852600426 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 25.

Adding to 21315010525 its reverse (52501051312), we get a palindrome (73816061837).

The spelling of 21315010525 in words is "twenty-one billion, three hundred fifteen million, ten thousand, five hundred twenty-five".