18066991 has 2 divisors, whose sum is σ = 18066992. Its totient is φ = 18066990.

The previous prime is 18066977. The next prime is 18067013. The reversal of 18066991 is 19966081.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18066991 - 2⁹ = 18066479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18066091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9033495 + 9033496.

It is an arithmetic number, because the mean of its divisors is an integer number (9033496).

Almost surely, 2^18066991 is an apocalyptic number.

18066991 is a deficient number, since it is larger than the sum of its proper divisors (1).

18066991 is an equidigital number, since it uses as much as digits as its factorization.

18066991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 18066991 is about 4250.5283201033. The cubic root of 18066991 is about 262.3988592972.

The spelling of 18066991 in words is "eighteen million, sixty-six thousand, nine hundred ninety-one".