166581581 has 8 divisors (see below), whose sum is σ = 169478400. Its totient is φ = 163706112.

The previous prime is 166581551. The next prime is 166581587. The reversal of 166581581 is 185185661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166581581 is a prime.

It is a super-2 number, since 2×166581581² = 55498846256919122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166581587) 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 7 ways as a sum of consecutive naturals, for example, 10820 + ... + 21218.

It is an arithmetic number, because the mean of its divisors is an integer number (21184800).

Almost surely, 2^166581581 is an apocalyptic number.

It is an amenable number.

166581581 is a deficient number, since it is larger than the sum of its proper divisors (2896819).

166581581 is a wasteful number, since it uses less digits than its factorization.

166581581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10675.

The product of its digits is 57600, while the sum is 41.

The square root of 166581581 is about 12906.6487129696. The cubic root of 166581581 is about 550.2275433145.

The spelling of 166581581 in words is "one hundred sixty-six million, five hundred eighty-one thousand, five hundred eighty-one".