166401 has 8 divisors (see below), whose sum is σ = 246560. Its totient is φ = 110916.

The previous prime is 166399. The next prime is 166403. The reversal of 166401 is 104661.

166401 is a `hidden beast` number, since 1 + 664 + 0 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (166399) and next prime (166403).

It is not a de Polignac number, because 166401 - 2¹ = 166399 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3055 + ... + 3108.

It is an arithmetic number, because the mean of its divisors is an integer number (30820).

It is a Proth number, since it is equal to 325 ⋅ 2⁹ + 1 and 325 < 2⁹.

2¹⁶⁶⁴⁰¹ is an apocalyptic number.

It is an amenable number.

166401 is a deficient number, since it is larger than the sum of its proper divisors (80159).

166401 is an equidigital number, since it uses as much as digits as its factorization.

166401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6172 (or 6166 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 166401 is about 407.9227868114. The cubic root of 166401 is about 55.0028648645.

It can be divided in two parts, 16640 and 1, that added together give a square (16641 = 129²).

The spelling of 166401 in words is "one hundred sixty-six thousand, four hundred one".