21117256723 has 8 divisors (see below), whose sum is σ = 21333209040. Its totient is φ = 20902134240.

The previous prime is 21117256709. The next prime is 21117256729. The reversal of 21117256723 is 32765271112.

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 21117256723 - 2⁵ = 21117256691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21117256729) 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, 156240 + ... + 258157.

It is an arithmetic number, because the mean of its divisors is an integer number (2666651130).

Almost surely, 2^21117256723 is an apocalyptic number.

21117256723 is a deficient number, since it is larger than the sum of its proper divisors (215952317).

21117256723 is a wasteful number, since it uses less digits than its factorization.

21117256723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414917.

The product of its digits is 35280, while the sum is 37.

The spelling of 21117256723 in words is "twenty-one billion, one hundred seventeen million, two hundred fifty-six thousand, seven hundred twenty-three".