18991319 has 2 divisors, whose sum is σ = 18991320. Its totient is φ = 18991318.

The previous prime is 18991309. The next prime is 18991361. The reversal of 18991319 is 91319981.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (91319981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18991319 - 2⁴ = 18991303 is a prime.

It is a super-2 number, since 2×18991319² = 721340394719522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18991309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9495659 + 9495660.

It is an arithmetic number, because the mean of its divisors is an integer number (9495660).

Almost surely, 2^18991319 is an apocalyptic number.

18991319 is a deficient number, since it is larger than the sum of its proper divisors (1).

18991319 is an equidigital number, since it uses as much as digits as its factorization.

18991319 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 18991319 is about 4357.9030507803. The cubic root of 18991319 is about 266.7995193924.

The spelling of 18991319 in words is "eighteen million, nine hundred ninety-one thousand, three hundred nineteen".