18999691 has 2 divisors, whose sum is σ = 18999692. Its totient is φ = 18999690.

The previous prime is 18999667. The next prime is 18999709. The reversal of 18999691 is 19699981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18999691 - 2⁹ = 18999179 is a prime.

It is not a weakly prime, because it can be changed into another prime (18999641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9499845 + 9499846.

It is an arithmetic number, because the mean of its divisors is an integer number (9499846).

Almost surely, 2^18999691 is an apocalyptic number.

18999691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18999691 is an equidigital number, since it uses as much as digits as its factorization.

18999691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 314928, while the sum is 52.

The square root of 18999691 is about 4358.8634986657. The cubic root of 18999691 is about 266.8387183098.

The spelling of 18999691 in words is "eighteen million, nine hundred ninety-nine thousand, six hundred ninety-one".