21708315 has 12 divisors (see below), whose sum is σ = 37627824. Its totient is φ = 11577744.

The previous prime is 21708301. The next prime is 21708319. The reversal of 21708315 is 51380712.

It is not a de Polignac number, because 21708315 - 2⁴ = 21708299 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21708319) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 241159 + ... + 241248.

It is an arithmetic number, because the mean of its divisors is an integer number (3135652).

Almost surely, 2^21708315 is an apocalyptic number.

21708315 is a deficient number, since it is larger than the sum of its proper divisors (15919509).

21708315 is a wasteful number, since it uses less digits than its factorization.

21708315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 482418 (or 482415 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21708315 is about 4659.2182820726. The cubic root of 21708315 is about 278.9600667400.

The spelling of 21708315 in words is "twenty-one million, seven hundred eight thousand, three hundred fifteen".