21667256423 has 4 divisors (see below), whose sum is σ = 22807638360. Its totient is φ = 20526874488.

The previous prime is 21667256389. The next prime is 21667256431. The reversal of 21667256423 is 32465276612.

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 21667256423 - 2⁸ = 21667256167 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21667216423) 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, 570190940 + ... + 570190977.

It is an arithmetic number, because the mean of its divisors is an integer number (5701909590).

Almost surely, 2^21667256423 is an apocalyptic number.

21667256423 is a deficient number, since it is larger than the sum of its proper divisors (1140381937).

21667256423 is a wasteful number, since it uses less digits than its factorization.

21667256423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1140381936.

The product of its digits is 725760, while the sum is 44.

The spelling of 21667256423 in words is "twenty-one billion, six hundred sixty-seven million, two hundred fifty-six thousand, four hundred twenty-three".