21238915 has 8 divisors (see below), whose sum is σ = 25712928. Its totient is φ = 16840320.

The previous prime is 21238901. The next prime is 21238939. The reversal of 21238915 is 51983212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21238915 - 2⁵ = 21238883 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18231 + ... + 19360.

It is an arithmetic number, because the mean of its divisors is an integer number (3214116).

Almost surely, 2^21238915 is an apocalyptic number.

21238915 is a deficient number, since it is larger than the sum of its proper divisors (4474013).

21238915 is a wasteful number, since it uses less digits than its factorization.

21238915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37709.

The product of its digits is 4320, while the sum is 31.

The square root of 21238915 is about 4608.5697347442. The cubic root of 21238915 is about 276.9347420201.

The spelling of 21238915 in words is "twenty-one million, two hundred thirty-eight thousand, nine hundred fifteen".