18157091 has 4 divisors (see below), whose sum is σ = 18165672. Its totient is φ = 18148512.

The previous prime is 18157081. The next prime is 18157099. The reversal of 18157091 is 19075181.

It is a semiprime because it is the product of two primes, 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 18157091 - 2¹⁰ = 18156067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18157099) 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, 1400 + ... + 6186.

It is an arithmetic number, because the mean of its divisors is an integer number (4541418).

Almost surely, 2^18157091 is an apocalyptic number.

18157091 is a deficient number, since it is larger than the sum of its proper divisors (8581).

18157091 is an equidigital number, since it uses as much as digits as its factorization.

18157091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8580.

The product of its (nonzero) digits is 2520, while the sum is 32.

The square root of 18157091 is about 4261.1138215260. The cubic root of 18157091 is about 262.8343301636.

The spelling of 18157091 in words is "eighteen million, one hundred fifty-seven thousand, ninety-one".