166889993 has 2 divisors, whose sum is σ = 166889994. Its totient is φ = 166889992.

The previous prime is 166889981. The next prime is 166890023. The reversal of 166889993 is 399988661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 166616464 + 273529 = 12908^2 + 523^2 .

It is a cyclic number.

It is not a de Polignac number, because 166889993 - 2¹⁸ = 166627849 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (166889953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83444996 + 83444997.

It is an arithmetic number, because the mean of its divisors is an integer number (83444997).

Almost surely, 2^166889993 is an apocalyptic number.

It is an amenable number.

166889993 is a deficient number, since it is larger than the sum of its proper divisors (1).

166889993 is an equidigital number, since it uses as much as digits as its factorization.

166889993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5038848, while the sum is 59.

The square root of 166889993 is about 12918.5909835400. The cubic root of 166889993 is about 550.5669008776.

The spelling of 166889993 in words is "one hundred sixty-six million, eight hundred eighty-nine thousand, nine hundred ninety-three".