21125169025 has 27 divisors (see below), whose sum is σ = 26887623483. Its totient is φ = 16464681600.

The previous prime is 21125168993. The next prime is 21125169031. The reversal of 21125169025 is 52096152112.

The square root of 21125169025 is 145345.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 18880683649 + 2244485376 = 137407^2 + 47376^2 .

It is not a de Polignac number, because 21125169025 - 2⁵ = 21125168993 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 29795371 + ... + 29796079.

Almost surely, 2^21125169025 is an apocalyptic number.

21125169025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21125169025 is the 145345-th square number.

21125169025 is the 72673-rd centered octagonal number.

It is an amenable number.

21125169025 is a deficient number, since it is larger than the sum of its proper divisors (5762454458).

21125169025 is an frugal number, since it uses more digits than its factorization.

21125169025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1510 (or 755 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 34.

The spelling of 21125169025 in words is "twenty-one billion, one hundred twenty-five million, one hundred sixty-nine thousand, twenty-five".