21608525 has 6 divisors (see below), whose sum is σ = 26794602. Its totient is φ = 17286800.

The previous prime is 21608497. The next prime is 21608527. The reversal of 21608525 is 52580612.

It can be written as a sum of positive squares in 3 ways, for example, as 51076 + 21557449 = 226^2 + 4643^2 .

It is not a de Polignac number, because 21608525 - 2¹⁴ = 21592141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21608527) 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, 432146 + ... + 432195.

It is an arithmetic number, because the mean of its divisors is an integer number (4465767).

Almost surely, 2^21608525 is an apocalyptic number.

21608525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21608525 is a deficient number, since it is larger than the sum of its proper divisors (5186077).

21608525 is an equidigital number, since it uses as much as digits as its factorization.

21608525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864351 (or 864346 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 21608525 is about 4648.4970689460. The cubic root of 21608525 is about 278.5319636651.

The spelling of 21608525 in words is "twenty-one million, six hundred eight thousand, five hundred twenty-five".