66993187 has 2 divisors, whose sum is σ = 66993188. Its totient is φ = 66993186.

The previous prime is 66993169. The next prime is 66993193. The reversal of 66993187 is 78139966.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66993187 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66993187.

It is not a weakly prime, because it can be changed into another prime (66993127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33496593 + 33496594.

It is an arithmetic number, because the mean of its divisors is an integer number (33496594).

Almost surely, 2^66993187 is an apocalyptic number.

66993187 is a deficient number, since it is larger than the sum of its proper divisors (1).

66993187 is an equidigital number, since it uses as much as digits as its factorization.

66993187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 489888, while the sum is 49.

The square root of 66993187 is about 8184.9365910800. The cubic root of 66993187 is about 406.1410427485.

The spelling of 66993187 in words is "sixty-six million, nine hundred ninety-three thousand, one hundred eighty-seven".