18949391 has 2 divisors, whose sum is σ = 18949392. Its totient is φ = 18949390.

The previous prime is 18949387. The next prime is 18949417. The reversal of 18949391 is 19394981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18949391 - 2² = 18949387 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18949321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9474695 + 9474696.

It is an arithmetic number, because the mean of its divisors is an integer number (9474696).

Almost surely, 2^18949391 is an apocalyptic number.

18949391 is a deficient number, since it is larger than the sum of its proper divisors (1).

18949391 is an equidigital number, since it uses as much as digits as its factorization.

18949391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 44.

The square root of 18949391 is about 4353.0898221838. The cubic root of 18949391 is about 266.6030329068.

The spelling of 18949391 in words is "eighteen million, nine hundred forty-nine thousand, three hundred ninety-one".