666202391 has 2 divisors, whose sum is σ = 666202392. Its totient is φ = 666202390.

The previous prime is 666202333. The next prime is 666202417. The reversal of 666202391 is 193202666.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666202391 is a prime.

It is a super-3 number, since 3×666202391³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666202331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333101195 + 333101196.

It is an arithmetic number, because the mean of its divisors is an integer number (333101196).

Almost surely, 2^666202391 is an apocalyptic number.

666202391 is a deficient number, since it is larger than the sum of its proper divisors (1).

666202391 is an equidigital number, since it uses as much as digits as its factorization.

666202391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 666202391 is about 25810.8967492414. The cubic root of 666202391 is about 873.3776265663.

The spelling of 666202391 in words is "six hundred sixty-six million, two hundred two thousand, three hundred ninety-one".