66786689 has 2 divisors, whose sum is σ = 66786690. Its totient is φ = 66786688.

The previous prime is 66786649. The next prime is 66786721. The reversal of 66786689 is 98668766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59985025 + 6801664 = 7745^2 + 2608^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66786689 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (66786619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33393344 + 33393345.

It is an arithmetic number, because the mean of its divisors is an integer number (33393345).

Almost surely, 2^66786689 is an apocalyptic number.

It is an amenable number.

66786689 is a deficient number, since it is larger than the sum of its proper divisors (1).

66786689 is an equidigital number, since it uses as much as digits as its factorization.

66786689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5225472, while the sum is 56.

The square root of 66786689 is about 8172.3123410697. The cubic root of 66786689 is about 405.7233205154.

The spelling of 66786689 in words is "sixty-six million, seven hundred eighty-six thousand, six hundred eighty-nine".