18913691 has 2 divisors, whose sum is σ = 18913692. Its totient is φ = 18913690.

The previous prime is 18913667. The next prime is 18913703. The reversal of 18913691 is 19631981.

It is a strong prime.

It is an emirp because it is prime and its reverse (19631981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18913691 - 2¹⁰ = 18912667 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18913621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9456845 + 9456846.

It is an arithmetic number, because the mean of its divisors is an integer number (9456846).

Almost surely, 2^18913691 is an apocalyptic number.

18913691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18913691 is an equidigital number, since it uses as much as digits as its factorization.

18913691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 38.

The square root of 18913691 is about 4348.9873533962. The cubic root of 18913691 is about 266.4355040125.

The spelling of 18913691 in words is "eighteen million, nine hundred thirteen thousand, six hundred ninety-one".