21647315 has 4 divisors (see below), whose sum is σ = 25976784. Its totient is φ = 17317848.

The previous prime is 21647299. The next prime is 21647321. The reversal of 21647315 is 51374612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21647315 - 2⁴ = 21647299 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2164727 + ... + 2164736.

It is an arithmetic number, because the mean of its divisors is an integer number (6494196).

Almost surely, 2^21647315 is an apocalyptic number.

21647315 is a deficient number, since it is larger than the sum of its proper divisors (4329469).

21647315 is an equidigital number, since it uses as much as digits as its factorization.

21647315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4329468.

The product of its digits is 5040, while the sum is 29.

The square root of 21647315 is about 4652.6675144480. The cubic root of 21647315 is about 278.6985305844.

The spelling of 21647315 in words is "twenty-one million, six hundred forty-seven thousand, three hundred fifteen".