18887161 has 4 divisors (see below), whose sum is σ = 19081972. Its totient is φ = 18692352.

The previous prime is 18887129. The next prime is 18887171. The reversal of 18887161 is 16178881.

It is a happy number.

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 6943225 + 11943936 = 2635^2 + 3456^2 .

It is a cyclic number.

It is not a de Polignac number, because 18887161 - 2⁵ = 18887129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18887171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97260 + ... + 97453.

It is an arithmetic number, because the mean of its divisors is an integer number (4770493).

Almost surely, 2^18887161 is an apocalyptic number.

It is an amenable number.

18887161 is a deficient number, since it is larger than the sum of its proper divisors (194811).

18887161 is an equidigital number, since it uses as much as digits as its factorization.

18887161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194810.

The product of its digits is 21504, while the sum is 40.

The square root of 18887161 is about 4345.9361477132. The cubic root of 18887161 is about 266.3108704604.

The spelling of 18887161 in words is "eighteen million, eight hundred eighty-seven thousand, one hundred sixty-one".