166166500509 has 6 divisors (see below), whose sum is σ = 240018278526. Its totient is φ = 110777667000.

The previous prime is 166166500481. The next prime is 166166500517. The reversal of 166166500509 is 905005661661.

It can be written as a sum of positive squares in only one way, i.e., 144991885284 + 21174615225 = 380778^2 + 145515^2 .

It is not a de Polignac number, because 166166500509 - 2⁵ = 166166500477 is a prime.

It is a super-2 number, since 2×166166500509² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166166500109) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9231472242 + ... + 9231472259.

It is an arithmetic number, because the mean of its divisors is an integer number (40003046421).

Almost surely, 2^166166500509 is an apocalyptic number.

It is an amenable number.

166166500509 is a deficient number, since it is larger than the sum of its proper divisors (73851778017).

166166500509 is a wasteful number, since it uses less digits than its factorization.

166166500509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18462944507 (or 18462944504 counting only the distinct ones).

The product of its (nonzero) digits is 291600, while the sum is 45.

The spelling of 166166500509 in words is "one hundred sixty-six billion, one hundred sixty-six million, five hundred thousand, five hundred nine".