66639959 has 2 divisors, whose sum is σ = 66639960. Its totient is φ = 66639958.

The previous prime is 66639929. The next prime is 66639967. The reversal of 66639959 is 95993666.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66639959 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66639959.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66639929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33319979 + 33319980.

It is an arithmetic number, because the mean of its divisors is an integer number (33319980).

Almost surely, 2^66639959 is an apocalyptic number.

66639959 is a deficient number, since it is larger than the sum of its proper divisors (1).

66639959 is an equidigital number, since it uses as much as digits as its factorization.

66639959 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2361960, while the sum is 53.

The square root of 66639959 is about 8163.3301415538. The cubic root of 66639959 is about 405.4259786647.

The spelling of 66639959 in words is "sixty-six million, six hundred thirty-nine thousand, nine hundred fifty-nine".