18481891 has 2 divisors, whose sum is σ = 18481892. Its totient is φ = 18481890.

The previous prime is 18481871. The next prime is 18481901. The reversal of 18481891 is 19818481.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18481891 - 2¹³ = 18473699 is a prime.

It is not a weakly prime, because it can be changed into another prime (18481831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9240945 + 9240946.

It is an arithmetic number, because the mean of its divisors is an integer number (9240946).

Almost surely, 2^18481891 is an apocalyptic number.

18481891 is a deficient number, since it is larger than the sum of its proper divisors (1).

18481891 is an equidigital number, since it uses as much as digits as its factorization.

18481891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18432, while the sum is 40.

The square root of 18481891 is about 4299.0569896199. The cubic root of 18481891 is about 264.3922991845.

The spelling of 18481891 in words is "eighteen million, four hundred eighty-one thousand, eight hundred ninety-one".