166399961 has 16 divisors (see below), whose sum is σ = 216849024. Its totient is φ = 123911424.

The previous prime is 166399949. The next prime is 166399993. The reversal of 166399961 is 169993661.

It is a happy number.

It is not a de Polignac number, because 166399961 - 2⁶ = 166399897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (166399061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52235 + ... + 55328.

It is an arithmetic number, because the mean of its divisors is an integer number (13553064).

Almost surely, 2^166399961 is an apocalyptic number.

It is an amenable number.

166399961 is a deficient number, since it is larger than the sum of its proper divisors (50449063).

166399961 is a wasteful number, since it uses less digits than its factorization.

166399961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107600.

The product of its digits is 472392, while the sum is 50.

The square root of 166399961 is about 12899.6108856043. The cubic root of 166399961 is about 550.0275038588.

The spelling of 166399961 in words is "one hundred sixty-six million, three hundred ninety-nine thousand, nine hundred sixty-one".