21002222525 has 12 divisors (see below), whose sum is σ = 26070578772. Its totient is φ = 16783827840.

The previous prime is 21002222513. The next prime is 21002222531. The reversal of 21002222525 is 52522220012.

It can be written as a sum of positive squares in 6 ways, for example, as 10814752036 + 10187470489 = 103994^2 + 100933^2 .

It is not a de Polignac number, because 21002222525 - 2⁴ = 21002222509 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 21002222525.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 424862 + ... + 471711.

It is an arithmetic number, because the mean of its divisors is an integer number (2172548231).

Almost surely, 2^21002222525 is an apocalyptic number.

21002222525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21002222525 is a deficient number, since it is larger than the sum of its proper divisors (5068356247).

21002222525 is an equidigital number, since it uses as much as digits as its factorization.

21002222525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 897520 (or 897515 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

Adding to 21002222525 its reverse (52522220012), we get a palindrome (73524442537).

The spelling of 21002222525 in words is "twenty-one billion, two million, two hundred twenty-two thousand, five hundred twenty-five".