18997859 has 4 divisors (see below), whose sum is σ = 19006680. Its totient is φ = 18989040.

The previous prime is 18997843. The next prime is 18997877. The reversal of 18997859 is 95879981.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 95879981 = 43 ⋅2229767.

It is a cyclic number.

It is not a de Polignac number, because 18997859 - 2⁴ = 18997843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18997819) 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, 1199 + ... + 6279.

It is an arithmetic number, because the mean of its divisors is an integer number (4751670).

Almost surely, 2^18997859 is an apocalyptic number.

18997859 is a deficient number, since it is larger than the sum of its proper divisors (8821).

18997859 is an equidigital number, since it uses as much as digits as its factorization.

18997859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8820.

The product of its digits is 1632960, while the sum is 56.

The square root of 18997859 is about 4358.6533470787. The cubic root of 18997859 is about 266.8301416046.

The spelling of 18997859 in words is "eighteen million, nine hundred ninety-seven thousand, eight hundred fifty-nine".