21660973513 has 2 divisors, whose sum is σ = 21660973514. Its totient is φ = 21660973512.

The previous prime is 21660973501. The next prime is 21660973549. The reversal of 21660973513 is 31537906612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21659597584 + 1375929 = 147172^2 + 1173^2 .

It is a cyclic number.

It is not a de Polignac number, because 21660973513 - 2⁹ = 21660973001 is a prime.

It is a super-3 number, since 3×21660973513³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 21660973513.

It is not a weakly prime, because it can be changed into another prime (21660974513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830486756 + 10830486757.

It is an arithmetic number, because the mean of its divisors is an integer number (10830486757).

Almost surely, 2^21660973513 is an apocalyptic number.

It is an amenable number.

21660973513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21660973513 is an equidigital number, since it uses as much as digits as its factorization.

21660973513 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 204120, while the sum is 43.

The spelling of 21660973513 in words is "twenty-one billion, six hundred sixty million, nine hundred seventy-three thousand, five hundred thirteen".