18666331 has 2 divisors, whose sum is σ = 18666332. Its totient is φ = 18666330.

The previous prime is 18666313. The next prime is 18666337. The reversal of 18666331 is 13366681.

It is a happy number.

Together with previous prime (18666313) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is an emirp because it is prime and its reverse (13366681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18666331 - 2⁷ = 18666203 is a prime.

It is a super-2 number, since 2×18666331² = 696863826003122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18666337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9333165 + 9333166.

It is an arithmetic number, because the mean of its divisors is an integer number (9333166).

Almost surely, 2^18666331 is an apocalyptic number.

18666331 is a deficient number, since it is larger than the sum of its proper divisors (1).

18666331 is an equidigital number, since it uses as much as digits as its factorization.

18666331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 34.

The square root of 18666331 is about 4320.4549528956. The cubic root of 18666331 is about 265.2688904730.

The spelling of 18666331 in words is "eighteen million, six hundred sixty-six thousand, three hundred thirty-one".