666390839 has 2 divisors, whose sum is σ = 666390840. Its totient is φ = 666390838.

The previous prime is 666390763. The next prime is 666390847. The reversal of 666390839 is 938093666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666390839 - 2⁸ = 666390583 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666393839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333195419 + 333195420.

It is an arithmetic number, because the mean of its divisors is an integer number (333195420).

Almost surely, 2^666390839 is an apocalyptic number.

666390839 is a deficient number, since it is larger than the sum of its proper divisors (1).

666390839 is an equidigital number, since it uses as much as digits as its factorization.

666390839 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1259712, while the sum is 50.

The square root of 666390839 is about 25814.5470423171. The cubic root of 666390839 is about 873.4599692862.

The spelling of 666390839 in words is "six hundred sixty-six million, three hundred ninety thousand, eight hundred thirty-nine".