18909091 has 2 divisors, whose sum is σ = 18909092. Its totient is φ = 18909090.

The previous prime is 18909089. The next prime is 18909097. The reversal of 18909091 is 19090981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18909091 - 2¹ = 18909089 is a prime.

Together with 18909089, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 18909091.

It is not a weakly prime, because it can be changed into another prime (18909097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9454545 + 9454546.

It is an arithmetic number, because the mean of its divisors is an integer number (9454546).

Almost surely, 2^18909091 is an apocalyptic number.

18909091 is a deficient number, since it is larger than the sum of its proper divisors (1).

18909091 is an equidigital number, since it uses as much as digits as its factorization.

18909091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 18909091 is about 4348.4584624899. The cubic root of 18909091 is about 266.4139023292.

The spelling of 18909091 in words is "eighteen million, nine hundred nine thousand, ninety-one".