18919939 has 2 divisors, whose sum is σ = 18919940. Its totient is φ = 18919938.

The previous prime is 18919907. The next prime is 18919949. The reversal of 18919939 is 93991981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18919939 - 2⁵ = 18919907 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 18919892 and 18919901.

It is not a weakly prime, because it can be changed into another prime (18919949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459969 + 9459970.

It is an arithmetic number, because the mean of its divisors is an integer number (9459970).

Almost surely, 2^18919939 is an apocalyptic number.

18919939 is a deficient number, since it is larger than the sum of its proper divisors (1).

18919939 is an equidigital number, since it uses as much as digits as its factorization.

18919939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 157464, while the sum is 49.

The square root of 18919939 is about 4349.7056222232. The cubic root of 18919939 is about 266.4648391250.

The spelling of 18919939 in words is "eighteen million, nine hundred nineteen thousand, nine hundred thirty-nine".