21097525 has 6 divisors (see below), whose sum is σ = 26160962. Its totient is φ = 16878000.

The previous prime is 21097513. The next prime is 21097547. The reversal of 21097525 is 52579012.

It can be written as a sum of positive squares in 3 ways, for example, as 93636 + 21003889 = 306^2 + 4583^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21097525 is a prime.

It is a super-2 number, since 2×21097525² = 890211122251250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 421926 + ... + 421975.

Almost surely, 2^21097525 is an apocalyptic number.

21097525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21097525 is a deficient number, since it is larger than the sum of its proper divisors (5063437).

21097525 is an equidigital number, since it uses as much as digits as its factorization.

21097525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 843911 (or 843906 counting only the distinct ones).

The product of its (nonzero) digits is 6300, while the sum is 31.

The square root of 21097525 is about 4593.2042192787. The cubic root of 21097525 is about 276.3188440447.

The spelling of 21097525 in words is "twenty-one million, ninety-seven thousand, five hundred twenty-five".