18918619 has 2 divisors, whose sum is σ = 18918620. Its totient is φ = 18918618.

The previous prime is 18918617. The next prime is 18918709. The reversal of 18918619 is 91681981.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (91681981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18918619 - 2¹ = 18918617 is a prime.

It is a super-2 number, since 2×18918619² = 715828289734322, which contains 22 as substring.

Together with 18918617, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18918617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459309 + 9459310.

It is an arithmetic number, because the mean of its divisors is an integer number (9459310).

Almost surely, 2^18918619 is an apocalyptic number.

18918619 is a deficient number, since it is larger than the sum of its proper divisors (1).

18918619 is an equidigital number, since it uses as much as digits as its factorization.

18918619 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 43.

The square root of 18918619 is about 4349.5538851703. The cubic root of 18918619 is about 266.4586421042.

The spelling of 18918619 in words is "eighteen million, nine hundred eighteen thousand, six hundred nineteen".