166391401 has 4 divisors (see below), whose sum is σ = 181517904. Its totient is φ = 151264900.

The previous prime is 166391399. The next prime is 166391413. The reversal of 166391401 is 104193661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 166391401 - 2¹ = 166391399 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166391431) 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 3 ways as a sum of consecutive naturals, for example, 7563235 + ... + 7563256.

It is an arithmetic number, because the mean of its divisors is an integer number (45379476).

Almost surely, 2^166391401 is an apocalyptic number.

166391401 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

166391401 is a deficient number, since it is larger than the sum of its proper divisors (15126503).

166391401 is a wasteful number, since it uses less digits than its factorization.

166391401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15126502.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 166391401 is about 12899.2790883832. The cubic root of 166391401 is about 550.0180721334.

The spelling of 166391401 in words is "one hundred sixty-six million, three hundred ninety-one thousand, four hundred one".