21723456 has 28 divisors (see below), whose sum is σ = 57477152. Its totient is φ = 7241088.

The previous prime is 21723451. The next prime is 21723463. The reversal of 21723456 is 65432712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21723451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56380 + ... + 56763.

Almost surely, 2^21723456 is an apocalyptic number.

It is an amenable number.

21723456 is an abundant number, since it is smaller than the sum of its proper divisors (35753696).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21723456 is a wasteful number, since it uses less digits than its factorization.

21723456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113158 (or 113148 counting only the distinct ones).

The product of its digits is 10080, while the sum is 30.

The square root of 21723456 is about 4660.8428422336. The cubic root of 21723456 is about 279.0249075283.

The spelling of 21723456 in words is "twenty-one million, seven hundred twenty-three thousand, four hundred fifty-six".