18993251 has 2 divisors, whose sum is σ = 18993252. Its totient is φ = 18993250.

The previous prime is 18993211. The next prime is 18993253. The reversal of 18993251 is 15239981.

It is a strong prime.

It is an emirp because it is prime and its reverse (15239981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18993251 - 2¹⁸ = 18731107 is a prime.

Together with 18993253, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18993253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9496625 + 9496626.

It is an arithmetic number, because the mean of its divisors is an integer number (9496626).

Almost surely, 2^18993251 is an apocalyptic number.

18993251 is a deficient number, since it is larger than the sum of its proper divisors (1).

18993251 is an equidigital number, since it uses as much as digits as its factorization.

18993251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 38.

The square root of 18993251 is about 4358.1247113868. The cubic root of 18993251 is about 266.8085663187.

The spelling of 18993251 in words is "eighteen million, nine hundred ninety-three thousand, two hundred fifty-one".