66916639 has 2 divisors, whose sum is σ = 66916640. Its totient is φ = 66916638.

The previous prime is 66916627. The next prime is 66916657. The reversal of 66916639 is 93661966.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66916639 - 2⁷ = 66916511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66916139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33458319 + 33458320.

It is an arithmetic number, because the mean of its divisors is an integer number (33458320).

Almost surely, 2^66916639 is an apocalyptic number.

66916639 is a deficient number, since it is larger than the sum of its proper divisors (1).

66916639 is an equidigital number, since it uses as much as digits as its factorization.

66916639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 314928, while the sum is 46.

The square root of 66916639 is about 8180.2591034759. The cubic root of 66916639 is about 405.9862950068.

The spelling of 66916639 in words is "sixty-six million, nine hundred sixteen thousand, six hundred thirty-nine".