21238815 has 16 divisors (see below), whose sum is σ = 36596448. Its totient is φ = 10455936.

The previous prime is 21238757. The next prime is 21238843. The reversal of 21238815 is 51883212.

It is not a de Polignac number, because 21238815 - 2⁷ = 21238687 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54264 + ... + 54653.

It is an arithmetic number, because the mean of its divisors is an integer number (2287278).

Almost surely, 2^21238815 is an apocalyptic number.

21238815 is a deficient number, since it is larger than the sum of its proper divisors (15357633).

21238815 is a wasteful number, since it uses less digits than its factorization.

21238815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108938.

The product of its digits is 3840, while the sum is 30.

The square root of 21238815 is about 4608.5588853784. The cubic root of 21238815 is about 276.9343073852.

The spelling of 21238815 in words is "twenty-one million, two hundred thirty-eight thousand, eight hundred fifteen".