166755581 has 2 divisors, whose sum is σ = 166755582. Its totient is φ = 166755580.

The previous prime is 166755557. The next prime is 166755587. The reversal of 166755581 is 185557661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 101808100 + 64947481 = 10090^2 + 8059^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166755581 is a prime.

It is a super-2 number, since 2×166755581² = 55614847589295122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166755587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83377790 + 83377791.

It is an arithmetic number, because the mean of its divisors is an integer number (83377791).

Almost surely, 2^166755581 is an apocalyptic number.

It is an amenable number.

166755581 is a deficient number, since it is larger than the sum of its proper divisors (1).

166755581 is an equidigital number, since it uses as much as digits as its factorization.

166755581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 252000, while the sum is 44.

The square root of 166755581 is about 12913.3876655198. The cubic root of 166755581 is about 550.4190536381.

The spelling of 166755581 in words is "one hundred sixty-six million, seven hundred fifty-five thousand, five hundred eighty-one".