21664725971 has 8 divisors (see below), whose sum is σ = 24863285760. Its totient is φ = 18492065928.

The previous prime is 21664725941. The next prime is 21664726009. The reversal of 21664725971 is 17952746612.

It is a happy number.

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

It is not a de Polignac number, because 21664725971 - 2³⁰ = 20590984147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21664725941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6473141 + ... + 6476486.

It is an arithmetic number, because the mean of its divisors is an integer number (3107910720).

Almost surely, 2^21664725971 is an apocalyptic number.

21664725971 is a deficient number, since it is larger than the sum of its proper divisors (3198559789).

21664725971 is a wasteful number, since it uses less digits than its factorization.

21664725971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12949873.

The product of its digits is 1270080, while the sum is 50.

The spelling of 21664725971 in words is "twenty-one billion, six hundred sixty-four million, seven hundred twenty-five thousand, nine hundred seventy-one".