21525985 has 24 divisors (see below), whose sum is σ = 28599480. Its totient is φ = 15459840.

The previous prime is 21525979. The next prime is 21525989. The reversal of 21525985 is 58952512.

It can be written as a sum of positive squares in 12 ways, for example, as 21095649 + 430336 = 4593^2 + 656^2 .

It is not a de Polignac number, because 21525985 - 2⁷ = 21525857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21525989) 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, 241821 + ... + 241909.

It is an arithmetic number, because the mean of its divisors is an integer number (1191645).

Almost surely, 2^21525985 is an apocalyptic number.

It is an amenable number.

21525985 is a deficient number, since it is larger than the sum of its proper divisors (7073495).

21525985 is an equidigital number, since it uses as much as digits as its factorization.

21525985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229 (or 168 counting only the distinct ones).

The product of its digits is 36000, while the sum is 37.

The square root of 21525985 is about 4639.6104362328. The cubic root of 21525985 is about 278.1768667314.

The spelling of 21525985 in words is "twenty-one million, five hundred twenty-five thousand, nine hundred eighty-five".