21685202923 has 4 divisors (see below), whose sum is σ = 21713849920. Its totient is φ = 21656555928.

The previous prime is 21685202899. The next prime is 21685202939. The reversal of 21685202923 is 32920258612.

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 21685202923 - 2⁹ = 21685202411 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21685202323) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14322363 + ... + 14323876.

It is an arithmetic number, because the mean of its divisors is an integer number (5428462480).

Almost surely, 2^21685202923 is an apocalyptic number.

21685202923 is a deficient number, since it is larger than the sum of its proper divisors (28646997).

21685202923 is an equidigital number, since it uses as much as digits as its factorization.

21685202923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28646996.

The product of its (nonzero) digits is 103680, while the sum is 40.

The spelling of 21685202923 in words is "twenty-one billion, six hundred eighty-five million, two hundred two thousand, nine hundred twenty-three".