21715315 has 8 divisors (see below), whose sum is σ = 26104320. Its totient is φ = 17341632.

The previous prime is 21715313. The next prime is 21715321. The reversal of 21715315 is 51351712.

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

It is a cyclic number.

It is not a de Polignac number, because 21715315 - 2¹ = 21715313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21715315.

It is not an unprimeable number, because it can be changed into a prime (21715313) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 435 + ... + 6604.

It is an arithmetic number, because the mean of its divisors is an integer number (3263040).

Almost surely, 2^21715315 is an apocalyptic number.

21715315 is a deficient number, since it is larger than the sum of its proper divisors (4389005).

21715315 is an equidigital number, since it uses as much as digits as its factorization.

21715315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7661.

The product of its digits is 1050, while the sum is 25.

The square root of 21715315 is about 4659.9694205005. The cubic root of 21715315 is about 278.9900477345.

The spelling of 21715315 in words is "twenty-one million, seven hundred fifteen thousand, three hundred fifteen".