18861971 has 4 divisors (see below), whose sum is σ = 19371792. Its totient is φ = 18352152.

The previous prime is 18861967. The next prime is 18861989. The reversal of 18861971 is 17916881.

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 18861971 - 2² = 18861967 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18861071) 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, 254855 + ... + 254928.

It is an arithmetic number, because the mean of its divisors is an integer number (4842948).

Almost surely, 2^18861971 is an apocalyptic number.

18861971 is a deficient number, since it is larger than the sum of its proper divisors (509821).

18861971 is an equidigital number, since it uses as much as digits as its factorization.

18861971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 509820.

The product of its digits is 24192, while the sum is 41.

The square root of 18861971 is about 4343.0370709908. The cubic root of 18861971 is about 266.1924239421.

The spelling of 18861971 in words is "eighteen million, eight hundred sixty-one thousand, nine hundred seventy-one".