16644163752521 has 2 divisors, whose sum is σ = 16644163752522. Its totient is φ = 16644163752520.

The previous prime is 16644163752481. The next prime is 16644163752529. The reversal of 16644163752521 is 12525736144661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12839573065225 + 3804590687296 = 3583235^2 + 1950536^2 .

It is a cyclic number.

It is not a de Polignac number, because 16644163752521 - 2¹⁰ = 16644163751497 is a prime.

It is a super-2 number, since 2×16644163752521² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (16644163752529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8322081876260 + 8322081876261.

It is an arithmetic number, because the mean of its divisors is an integer number (8322081876261).

Almost surely, 2^{16644163752521} is an apocalyptic number.

It is an amenable number.

16644163752521 is a deficient number, since it is larger than the sum of its proper divisors (1).

16644163752521 is an equidigital number, since it uses as much as digits as its factorization.

16644163752521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7257600, while the sum is 53.

The spelling of 16644163752521 in words is "sixteen trillion, six hundred forty-four billion, one hundred sixty-three million, seven hundred fifty-two thousand, five hundred twenty-one".