18156939 has 4 divisors (see below), whose sum is σ = 24209256. Its totient is φ = 12104624.

The previous prime is 18156923. The next prime is 18156947. The reversal of 18156939 is 93965181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93965181 = 3 ⋅31321727.

It is a cyclic number.

It is not a de Polignac number, because 18156939 - 2⁴ = 18156923 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18156939.

It is not an unprimeable number, because it can be changed into a prime (18156949) 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, 3026154 + ... + 3026159.

It is an arithmetic number, because the mean of its divisors is an integer number (6052314).

Almost surely, 2^18156939 is an apocalyptic number.

18156939 is a deficient number, since it is larger than the sum of its proper divisors (6052317).

18156939 is an equidigital number, since it uses as much as digits as its factorization.

18156939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6052316.

The product of its digits is 58320, while the sum is 42.

The square root of 18156939 is about 4261.0959857764. The cubic root of 18156939 is about 262.8335967324.

The spelling of 18156939 in words is "eighteen million, one hundred fifty-six thousand, nine hundred thirty-nine".