21315239 has 6 divisors (see below), whose sum is σ = 23429280. Its totient is φ = 19377380.

The previous prime is 21315223. The next prime is 21315241. The reversal of 21315239 is 93251312.

It is not a de Polignac number, because 21315239 - 2⁴ = 21315223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315269) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87959 + ... + 88200.

It is an arithmetic number, because the mean of its divisors is an integer number (3904880).

Almost surely, 2^21315239 is an apocalyptic number.

21315239 is a deficient number, since it is larger than the sum of its proper divisors (2114041).

21315239 is a wasteful number, since it uses less digits than its factorization.

21315239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176181 (or 176170 counting only the distinct ones).

The product of its digits is 1620, while the sum is 26.

The square root of 21315239 is about 4616.8429689562. The cubic root of 21315239 is about 277.2660756233.

The spelling of 21315239 in words is "twenty-one million, three hundred fifteen thousand, two hundred thirty-nine".