18772161 has 4 divisors (see below), whose sum is σ = 25029552. Its totient is φ = 12514772.

The previous prime is 18772157. The next prime is 18772177. The reversal of 18772161 is 16127781.

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.

It is a cyclic number.

It is not a de Polignac number, because 18772161 - 2² = 18772157 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18772121) 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, 3128691 + ... + 3128696.

It is an arithmetic number, because the mean of its divisors is an integer number (6257388).

Almost surely, 2^18772161 is an apocalyptic number.

It is an amenable number.

18772161 is a deficient number, since it is larger than the sum of its proper divisors (6257391).

18772161 is an equidigital number, since it uses as much as digits as its factorization.

18772161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6257390.

The product of its digits is 4704, while the sum is 33.

The square root of 18772161 is about 4332.6851951186. The cubic root of 18772161 is about 265.7692658722.

The spelling of 18772161 in words is "eighteen million, seven hundred seventy-two thousand, one hundred sixty-one".