166806079561 has 27 divisors (see below), whose sum is σ = 185613290317. Its totient is φ = 149791752440.

The previous prime is 166806079553. The next prime is 166806079571. The reversal of 166806079561 is 165970608661.

It is a happy number.

The square root of 166806079561 is 408419.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 166806079561 - 2³ = 166806079553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166806079571) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 480708990 + ... + 480709336.

Almost surely, 2^166806079561 is an apocalyptic number.

166806079561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

166806079561 is the 408419-th square number.

166806079561 is the 204210-th centered octagonal number.

It is an amenable number.

166806079561 is a deficient number, since it is larger than the sum of its proper divisors (18807210756).

166806079561 is an frugal number, since it uses more digits than its factorization.

166806079561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 930 (or 465 counting only the distinct ones).

The product of its (nonzero) digits is 3265920, while the sum is 55.

The spelling of 166806079561 in words is "one hundred sixty-six billion, eight hundred six million, seventy-nine thousand, five hundred sixty-one".