166878989 has 4 divisors (see below), whose sum is σ = 166935324. Its totient is φ = 166822656.

The previous prime is 166878947. The next prime is 166878997. The reversal of 166878989 is 989878661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 151536100 + 15342889 = 12310^2 + 3917^2 .

It is a cyclic number.

It is not a de Polignac number, because 166878989 - 2¹² = 166874893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166878289) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23462 + ... + 29735.

It is an arithmetic number, because the mean of its divisors is an integer number (41733831).

Almost surely, 2^166878989 is an apocalyptic number.

It is an amenable number.

166878989 is a deficient number, since it is larger than the sum of its proper divisors (56335).

166878989 is an equidigital number, since it uses as much as digits as its factorization.

166878989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56334.

The product of its digits is 10450944, while the sum is 62.

The square root of 166878989 is about 12918.1650786789. The cubic root of 166878989 is about 550.5547999496.

The spelling of 166878989 in words is "one hundred sixty-six million, eight hundred seventy-eight thousand, nine hundred eighty-nine".