18891251 has 2 divisors, whose sum is σ = 18891252. Its totient is φ = 18891250.

The previous prime is 18891193. The next prime is 18891289. The reversal of 18891251 is 15219881.

It is a strong prime.

It is an emirp because it is prime and its reverse (15219881) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18891251 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18894251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9445625 + 9445626.

It is an arithmetic number, because the mean of its divisors is an integer number (9445626).

Almost surely, 2^18891251 is an apocalyptic number.

18891251 is a deficient number, since it is larger than the sum of its proper divisors (1).

18891251 is an equidigital number, since it uses as much as digits as its factorization.

18891251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 35.

The square root of 18891251 is about 4346.4066767849. The cubic root of 18891251 is about 266.3300922101.

The spelling of 18891251 in words is "eighteen million, eight hundred ninety-one thousand, two hundred fifty-one".