18561971 has 4 divisors (see below), whose sum is σ = 19014744. Its totient is φ = 18109200.

The previous prime is 18561967. The next prime is 18561979. The reversal of 18561971 is 17916581.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18561971 - 2² = 18561967 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18561979) 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, 226325 + ... + 226406.

It is an arithmetic number, because the mean of its divisors is an integer number (4753686).

Almost surely, 2^18561971 is an apocalyptic number.

18561971 is a deficient number, since it is larger than the sum of its proper divisors (452773).

18561971 is an equidigital number, since it uses as much as digits as its factorization.

18561971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 452772.

The product of its digits is 15120, while the sum is 38.

The square root of 18561971 is about 4308.3605930795. The cubic root of 18561971 is about 264.7736099010.

The spelling of 18561971 in words is "eighteen million, five hundred sixty-one thousand, nine hundred seventy-one".