166989961 has 2 divisors, whose sum is σ = 166989962. Its totient is φ = 166989960.

The previous prime is 166989923. The next prime is 166989971. The reversal of 166989961 is 169989661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 165379600 + 1610361 = 12860^2 + 1269^2 .

It is a cyclic number.

It is not a de Polignac number, because 166989961 - 2⁷ = 166989833 is a prime.

It is not a weakly prime, because it can be changed into another prime (166989971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83494980 + 83494981.

It is an arithmetic number, because the mean of its divisors is an integer number (83494981).

Almost surely, 2^166989961 is an apocalyptic number.

It is an amenable number.

166989961 is a deficient number, since it is larger than the sum of its proper divisors (1).

166989961 is an equidigital number, since it uses as much as digits as its factorization.

166989961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1259712, while the sum is 55.

The square root of 166989961 is about 12922.4595569110. The cubic root of 166989961 is about 550.6768097764.

The spelling of 166989961 in words is "one hundred sixty-six million, nine hundred eighty-nine thousand, nine hundred sixty-one".