21664425723 has 8 divisors (see below), whose sum is σ = 29251545600. Its totient is φ = 14260128168.

The previous prime is 21664425721. The next prime is 21664425737. The reversal of 21664425723 is 32752446612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21664425723 - 2¹ = 21664425721 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21664425721) 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, 45705303 + ... + 45705776.

It is an arithmetic number, because the mean of its divisors is an integer number (3656443200).

Almost surely, 2^21664425723 is an apocalyptic number.

21664425723 is a deficient number, since it is larger than the sum of its proper divisors (7587119877).

21664425723 is an equidigital number, since it uses as much as digits as its factorization.

21664425723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91411161.

The product of its digits is 483840, while the sum is 42.

The spelling of 21664425723 in words is "twenty-one billion, six hundred sixty-four million, four hundred twenty-five thousand, seven hundred twenty-three".