21002312525 has 24 divisors (see below), whose sum is σ = 26789071848. Its totient is φ = 16323840000.

The previous prime is 21002312521. The next prime is 21002312531. The reversal of 21002312525 is 52521320012.

It can be written as a sum of positive squares in 12 ways, for example, as 9841235209 + 11161077316 = 99203^2 + 105646^2 .

It is not a de Polignac number, because 21002312525 - 2² = 21002312521 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21002312525.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002312521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 204515 + ... + 289535.

It is an arithmetic number, because the mean of its divisors is an integer number (1116211327).

Almost surely, 2^21002312525 is an apocalyptic number.

21002312525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21002312525 is a deficient number, since it is larger than the sum of its proper divisors (5786759323).

21002312525 is a wasteful number, since it uses less digits than its factorization.

21002312525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85313 (or 85308 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

Adding to 21002312525 its reverse (52521320012), we get a palindrome (73523632537).

The spelling of 21002312525 in words is "twenty-one billion, two million, three hundred twelve thousand, five hundred twenty-five".