21722623 has 4 divisors (see below), whose sum is σ = 23393608. Its totient is φ = 20051640.

The previous prime is 21722609. The next prime is 21722627. The reversal of 21722623 is 32622712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21722623 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 (21722627) 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, 835473 + ... + 835498.

It is an arithmetic number, because the mean of its divisors is an integer number (5848402).

Almost surely, 2^21722623 is an apocalyptic number.

21722623 is a deficient number, since it is larger than the sum of its proper divisors (1670985).

21722623 is a wasteful number, since it uses less digits than its factorization.

21722623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1670984.

The product of its digits is 2016, while the sum is 25.

The square root of 21722623 is about 4660.7534798571. The cubic root of 21722623 is about 279.0213410190.

The spelling of 21722623 in words is "twenty-one million, seven hundred twenty-two thousand, six hundred twenty-three".