21663470657 has 8 divisors (see below), whose sum is σ = 21739228896. Its totient is φ = 21587746752.

The previous prime is 21663470639. The next prime is 21663470669. The reversal of 21663470657 is 75607436612.

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

It is a cyclic number.

It is not a de Polignac number, because 21663470657 - 2⁶ = 21663470593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21663470057) 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, 2366393 + ... + 2375529.

It is an arithmetic number, because the mean of its divisors is an integer number (2717403612).

Almost surely, 2^21663470657 is an apocalyptic number.

It is an amenable number.

21663470657 is a deficient number, since it is larger than the sum of its proper divisors (75758239).

21663470657 is an equidigital number, since it uses as much as digits as its factorization.

21663470657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17167.

The product of its (nonzero) digits is 1270080, while the sum is 47.

The spelling of 21663470657 in words is "twenty-one billion, six hundred sixty-three million, four hundred seventy thousand, six hundred fifty-seven".