166636401 has 4 divisors (see below), whose sum is σ = 222181872. Its totient is φ = 111090932.

The previous prime is 166636381. The next prime is 166636411. The reversal of 166636401 is 104636661.

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, and also an emirpimes, since its reverse is a distinct semiprime: 104636661 = 3 ⋅34878887.

It is a cyclic number.

It is not a de Polignac number, because 166636401 - 2⁵ = 166636369 is a prime.

It is not an unprimeable number, because it can be changed into a prime (166636411) 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, 27772731 + ... + 27772736.

It is an arithmetic number, because the mean of its divisors is an integer number (55545468).

Almost surely, 2^166636401 is an apocalyptic number.

It is an amenable number.

166636401 is a deficient number, since it is larger than the sum of its proper divisors (55545471).

166636401 is an equidigital number, since it uses as much as digits as its factorization.

166636401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55545470.

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 166636401 is about 12908.7722499082. The cubic root of 166636401 is about 550.2878944560.

The spelling of 166636401 in words is "one hundred sixty-six million, six hundred thirty-six thousand, four hundred one".