16566267077981 has 4 divisors (see below), whose sum is σ = 16566760316700. Its totient is φ = 16565773839264.

The previous prime is 16566267077977. The next prime is 16566267077989. The reversal of 16566267077981 is 18977076266561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7434592956025 + 9131674121956 = 2726645^2 + 3021866^2 .

It is a cyclic number.

It is not a de Polignac number, because 16566267077981 - 2² = 16566267077977 is a prime.

It is a super-2 number, since 2×16566267077981² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16566267077989) 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 in 3 ways as a sum of consecutive naturals, for example, 246568976 + ... + 246636153.

It is an arithmetic number, because the mean of its divisors is an integer number (4141690079175).

Almost surely, 2^{16566267077981} is an apocalyptic number.

It is an amenable number.

16566267077981 is a deficient number, since it is larger than the sum of its proper divisors (493238719).

16566267077981 is an equidigital number, since it uses as much as digits as its factorization.

16566267077981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493238718.

The product of its (nonzero) digits is 320060160, while the sum is 71.

The spelling of 16566267077981 in words is "sixteen trillion, five hundred sixty-six billion, two hundred sixty-seven million, seventy-seven thousand, nine hundred eighty-one".