21250915 has 32 divisors (see below), whose sum is σ = 30481920. Its totient is φ = 13920000.

The previous prime is 21250877. The next prime is 21250961. The reversal of 21250915 is 51905212.

It is not a de Polignac number, because 21250915 - 2⁷ = 21250787 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21250915.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 84540 + ... + 84790.

It is an arithmetic number, because the mean of its divisors is an integer number (952560).

Almost surely, 2^21250915 is an apocalyptic number.

21250915 is a deficient number, since it is larger than the sum of its proper divisors (9231005).

21250915 is a wasteful number, since it uses less digits than its factorization.

21250915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 21250915 is about 4609.8714732626. The cubic root of 21250915 is about 276.9868883001.

The spelling of 21250915 in words is "twenty-one million, two hundred fifty thousand, nine hundred fifteen".