18993911 has 2 divisors, whose sum is σ = 18993912. Its totient is φ = 18993910.

The previous prime is 18993907. The next prime is 18993937. The reversal of 18993911 is 11939981.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18993911 - 2² = 18993907 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18993941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9496955 + 9496956.

It is an arithmetic number, because the mean of its divisors is an integer number (9496956).

Almost surely, 2^18993911 is an apocalyptic number.

18993911 is a deficient number, since it is larger than the sum of its proper divisors (1).

18993911 is an equidigital number, since it uses as much as digits as its factorization.

18993911 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 41.

The square root of 18993911 is about 4358.2004313707. The cubic root of 18993911 is about 266.8116567430.

The spelling of 18993911 in words is "eighteen million, nine hundred ninety-three thousand, nine hundred eleven".