16399181 has 4 divisors (see below), whose sum is σ = 16964700. Its totient is φ = 15833664.

The previous prime is 16399171. The next prime is 16399183. The reversal of 16399181 is 18199361.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10023556 + 6375625 = 3166^2 + 2525^2 .

It is a cyclic number.

It is not a de Polignac number, because 16399181 - 2¹⁰ = 16398157 is a prime.

It is a super-2 number, since 2×16399181² = 537866274941522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16399183) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 282716 + ... + 282773.

It is an arithmetic number, because the mean of its divisors is an integer number (4241175).

Almost surely, 2^16399181 is an apocalyptic number.

It is an amenable number.

16399181 is a deficient number, since it is larger than the sum of its proper divisors (565519).

16399181 is an equidigital number, since it uses as much as digits as its factorization.

16399181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 565518.

The product of its digits is 11664, while the sum is 38.

The square root of 16399181 is about 4049.5902261834. The cubic root of 16399181 is about 254.0625892011.

The spelling of 16399181 in words is "sixteen million, three hundred ninety-nine thousand, one hundred eighty-one".