21525918 has 16 divisors (see below), whose sum is σ = 43215120. Its totient is φ = 7148096.

The previous prime is 21525901. The next prime is 21525937. The reversal of 21525918 is 81952512.

21525918 is a modest number, since divided by 5918 gives 2152 as remainder.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5055 + ... + 8282.

It is an arithmetic number, because the mean of its divisors is an integer number (2700945).

Almost surely, 2^21525918 is an apocalyptic number.

21525918 is an abundant number, since it is smaller than the sum of its proper divisors (21689202).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21525918 is a wasteful number, since it uses less digits than its factorization.

21525918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13611.

The product of its digits is 7200, while the sum is 33.

The square root of 21525918 is about 4639.6032157934. The cubic root of 21525918 is about 278.1765781210.

The spelling of 21525918 in words is "twenty-one million, five hundred twenty-five thousand, nine hundred eighteen".