166558987 has 12 divisors (see below), whose sum is σ = 194124216. Its totient is φ = 142490880.

The previous prime is 166558957. The next prime is 166558993. The reversal of 166558987 is 789855661.

It is not a de Polignac number, because 166558987 - 2¹⁵ = 166526219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166558927) 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 11 ways as a sum of consecutive naturals, for example, 25003 + ... + 30955.

It is an arithmetic number, because the mean of its divisors is an integer number (16177018).

Almost surely, 2^166558987 is an apocalyptic number.

166558987 is a deficient number, since it is larger than the sum of its proper divisors (27565229).

166558987 is an equidigital number, since it uses as much as digits as its factorization.

166558987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6538 (or 6531 counting only the distinct ones).

The product of its digits is 3628800, while the sum is 55.

The square root of 166558987 is about 12905.7733979797. The cubic root of 166558987 is about 550.2026658077.

It can be divided in two parts, 166 and 558987, that added together give a triangular number (559153 = T₁₀₅₇).

The spelling of 166558987 in words is "one hundred sixty-six million, five hundred fifty-eight thousand, nine hundred eighty-seven".