166603891 has 4 divisors (see below), whose sum is σ = 166670784. Its totient is φ = 166537000.

The previous prime is 166603841. The next prime is 166603907. The reversal of 166603891 is 198306661.

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

It is a cyclic number.

It is not a de Polignac number, because 166603891 - 2⁷ = 166603763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166603841) 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, 29560 + ... + 34741.

It is an arithmetic number, because the mean of its divisors is an integer number (41667696).

Almost surely, 2^166603891 is an apocalyptic number.

166603891 is a deficient number, since it is larger than the sum of its proper divisors (66893).

166603891 is an equidigital number, since it uses as much as digits as its factorization.

166603891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66892.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 166603891 is about 12907.5129672606. The cubic root of 166603891 is about 550.2521059111.

The spelling of 166603891 in words is "one hundred sixty-six million, six hundred three thousand, eight hundred ninety-one".