66766709 has 2 divisors, whose sum is σ = 66766710. Its totient is φ = 66766708.

The previous prime is 66766691. The next prime is 66766717. The reversal of 66766709 is 90766766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48302500 + 18464209 = 6950^2 + 4297^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66766709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66706709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33383354 + 33383355.

It is an arithmetic number, because the mean of its divisors is an integer number (33383355).

Almost surely, 2^66766709 is an apocalyptic number.

It is an amenable number.

66766709 is a deficient number, since it is larger than the sum of its proper divisors (1).

66766709 is an equidigital number, since it uses as much as digits as its factorization.

66766709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 571536, while the sum is 47.

The square root of 66766709 is about 8171.0898293924. The cubic root of 66766709 is about 405.6828575600.

It can be divided in two parts, 667 and 66709, that added together give a palindrome (67376).

The spelling of 66766709 in words is "sixty-six million, seven hundred sixty-six thousand, seven hundred nine".