166591409 has 2 divisors, whose sum is σ = 166591410. Its totient is φ = 166591408.

The previous prime is 166591393. The next prime is 166591423. The reversal of 166591409 is 904195661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 88887184 + 77704225 = 9428^2 + 8815^2 .

It is a cyclic number.

It is not a de Polignac number, because 166591409 - 2⁴ = 166591393 is a prime.

It is not a weakly prime, because it can be changed into another prime (166591429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83295704 + 83295705.

It is an arithmetic number, because the mean of its divisors is an integer number (83295705).

Almost surely, 2^166591409 is an apocalyptic number.

It is an amenable number.

166591409 is a deficient number, since it is larger than the sum of its proper divisors (1).

166591409 is an equidigital number, since it uses as much as digits as its factorization.

166591409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 58320, while the sum is 41.

The square root of 166591409 is about 12907.0294413548. The cubic root of 166591409 is about 550.2383638984.

The spelling of 166591409 in words is "one hundred sixty-six million, five hundred ninety-one thousand, four hundred nine".