18087661 has 4 divisors (see below), whose sum is σ = 18098752. Its totient is φ = 18076572.

The previous prime is 18087647. The next prime is 18087679. The reversal of 18087661 is 16678081.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 18087661 - 2⁷ = 18087533 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18087661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18087611) 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, 2565 + ... + 6538.

It is an arithmetic number, because the mean of its divisors is an integer number (4524688).

Almost surely, 2^18087661 is an apocalyptic number.

It is an amenable number.

18087661 is a deficient number, since it is larger than the sum of its proper divisors (11091).

18087661 is an equidigital number, since it uses as much as digits as its factorization.

18087661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11090.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 18087661 is about 4252.9590875060. The cubic root of 18087661 is about 262.4988891865.

The spelling of 18087661 in words is "eighteen million, eighty-seven thousand, six hundred sixty-one".