21207956815 has 8 divisors (see below), whose sum is σ = 25483171680. Its totient is φ = 16943949792.

The previous prime is 21207956767. The next prime is 21207956821. The reversal of 21207956815 is 51865970212.

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 21207956815 - 2²⁵ = 21174402383 is a prime.

It is a congruent 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, 2797795 + ... + 2805364.

It is an arithmetic number, because the mean of its divisors is an integer number (3185396460).

Almost surely, 2^21207956815 is an apocalyptic number.

21207956815 is a deficient number, since it is larger than the sum of its proper divisors (4275214865).

21207956815 is an equidigital number, since it uses as much as digits as its factorization.

21207956815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5603921.

The product of its (nonzero) digits is 302400, while the sum is 46.

The spelling of 21207956815 in words is "twenty-one billion, two hundred seven million, nine hundred fifty-six thousand, eight hundred fifteen".