18621091 has 2 divisors, whose sum is σ = 18621092. Its totient is φ = 18621090.

The previous prime is 18621089. The next prime is 18621139. The reversal of 18621091 is 19012681.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18621091 - 2¹ = 18621089 is a prime.

Together with 18621089, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18624091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9310545 + 9310546.

It is an arithmetic number, because the mean of its divisors is an integer number (9310546).

Almost surely, 2^18621091 is an apocalyptic number.

18621091 is a deficient number, since it is larger than the sum of its proper divisors (1).

18621091 is an equidigital number, since it uses as much as digits as its factorization.

18621091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 18621091 is about 4315.2162170626. The cubic root of 18621091 is about 265.0544138884.

The spelling of 18621091 in words is "eighteen million, six hundred twenty-one thousand, ninety-one".