166405391 has 8 divisors (see below), whose sum is σ = 178334304. Its totient is φ = 154867680.

The previous prime is 166405373. The next prime is 166405397. The reversal of 166405391 is 193504661.

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-166405391 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 (166405397) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96920 + ... + 98621.

It is an arithmetic number, because the mean of its divisors is an integer number (22291788).

Almost surely, 2^166405391 is an apocalyptic number.

166405391 is a deficient number, since it is larger than the sum of its proper divisors (11928913).

166405391 is a wasteful number, since it uses less digits than its factorization.

166405391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195601.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 166405391 is about 12899.8213553522. The cubic root of 166405391 is about 550.0334866664.

The spelling of 166405391 in words is "one hundred sixty-six million, four hundred five thousand, three hundred ninety-one".