18666919 has 2 divisors, whose sum is σ = 18666920. Its totient is φ = 18666918.

The previous prime is 18666917. The next prime is 18666941. The reversal of 18666919 is 91966681.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18666919 - 2¹ = 18666917 is a prime.

It is a super-2 number, since 2×18666919² = 696907729905122, which contains 22 as substring.

Together with 18666917, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18666917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9333459 + 9333460.

It is an arithmetic number, because the mean of its divisors is an integer number (9333460).

Almost surely, 2^18666919 is an apocalyptic number.

18666919 is a deficient number, since it is larger than the sum of its proper divisors (1).

18666919 is an equidigital number, since it uses as much as digits as its factorization.

18666919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 139968, while the sum is 46.

The square root of 18666919 is about 4320.5230007489. The cubic root of 18666919 is about 265.2716758172.

The spelling of 18666919 in words is "eighteen million, six hundred sixty-six thousand, nine hundred nineteen".