18686971 has 4 divisors (see below), whose sum is σ = 19499472. Its totient is φ = 17874472.

The previous prime is 18686959. The next prime is 18686977. The reversal of 18686971 is 17968681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17968681 = 23 ⋅781247.

It is a cyclic number.

It is not a de Polignac number, because 18686971 - 2¹⁷ = 18555899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18686977) 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, 406216 + ... + 406261.

It is an arithmetic number, because the mean of its divisors is an integer number (4874868).

Almost surely, 2^18686971 is an apocalyptic number.

18686971 is a deficient number, since it is larger than the sum of its proper divisors (812501).

18686971 is an equidigital number, since it uses as much as digits as its factorization.

18686971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812500.

The product of its digits is 145152, while the sum is 46.

The square root of 18686971 is about 4322.8429302948. The cubic root of 18686971 is about 265.3666267505.

The spelling of 18686971 in words is "eighteen million, six hundred eighty-six thousand, nine hundred seventy-one".