18943999 has 2 divisors, whose sum is σ = 18944000. Its totient is φ = 18943998.

The previous prime is 18943993. The next prime is 18944017. The reversal of 18943999 is 99934981.

It is a weak prime.

It is an emirp because it is prime and its reverse (99934981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18943999 - 2⁷ = 18943871 is a prime.

It is a super-2 number, since 2×18943999² = 717750196224002, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18943993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9471999 + 9472000.

It is an arithmetic number, because the mean of its divisors is an integer number (9472000).

Almost surely, 2^18943999 is an apocalyptic number.

18943999 is a deficient number, since it is larger than the sum of its proper divisors (1).

18943999 is an equidigital number, since it uses as much as digits as its factorization.

18943999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 629856, while the sum is 52.

The square root of 18943999 is about 4352.4704479181. The cubic root of 18943999 is about 266.5777434410.

The spelling of 18943999 in words is "eighteen million, nine hundred forty-three thousand, nine hundred ninety-nine".