18919091 has 2 divisors, whose sum is σ = 18919092. Its totient is φ = 18919090.

The previous prime is 18919067. The next prime is 18919111. The reversal of 18919091 is 19091981.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (19091981) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 16061681 and 18616061.

It is a cyclic number.

It is not a de Polignac number, because 18919091 - 2⁶ = 18919027 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18919391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459545 + 9459546.

It is an arithmetic number, because the mean of its divisors is an integer number (9459546).

Almost surely, 2^18919091 is an apocalyptic number.

18919091 is a deficient number, since it is larger than the sum of its proper divisors (1).

18919091 is an equidigital number, since it uses as much as digits as its factorization.

18919091 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 38.

The square root of 18919091 is about 4349.6081432699. The cubic root of 18919091 is about 266.4608580417.

The spelling of 18919091 in words is "eighteen million, nine hundred nineteen thousand, ninety-one".