401991165 has 12 divisors (see below), whose sum is σ = 696784764. Its totient is φ = 214395264.

The previous prime is 401991077. The next prime is 401991169. The reversal of 401991165 is 561199104.

401991165 is a `hidden beast` number, since 401 + 9 + 91 + 165 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 131125401 + 270865764 = 11451^2 + 16458^2 .

It is not a de Polignac number, because 401991165 - 2¹¹ = 401989117 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (401991169) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4466524 + ... + 4466613.

It is an arithmetic number, because the mean of its divisors is an integer number (58065397).

Almost surely, 2^401991165 is an apocalyptic number.

401991165 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

401991165 is a deficient number, since it is larger than the sum of its proper divisors (294793599).

401991165 is a wasteful number, since it uses less digits than its factorization.

401991165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8933148 (or 8933145 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 401991165 is about 20049.7173296782. The cubic root of 401991165 is about 738.0268624413.

The spelling of 401991165 in words is "four hundred one million, nine hundred ninety-one thousand, one hundred sixty-five".