18378791 has 2 divisors, whose sum is σ = 18378792. Its totient is φ = 18378790.

The previous prime is 18378781. The next prime is 18378793. The reversal of 18378791 is 19787381.

It is a strong prime.

It is an emirp because it is prime and its reverse (19787381) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18378791 is a prime.

It is a Sophie Germain prime.

Together with 18378793, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18378793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9189395 + 9189396.

It is an arithmetic number, because the mean of its divisors is an integer number (9189396).

Almost surely, 2^18378791 is an apocalyptic number.

18378791 is a deficient number, since it is larger than the sum of its proper divisors (1).

18378791 is an equidigital number, since it uses as much as digits as its factorization.

18378791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 44.

The square root of 18378791 is about 4287.0492182852. The cubic root of 18378791 is about 263.8997505426.

The spelling of 18378791 in words is "eighteen million, three hundred seventy-eight thousand, seven hundred ninety-one".