66828709 has 2 divisors, whose sum is σ = 66828710. Its totient is φ = 66828708.

The previous prime is 66828677. The next prime is 66828739. The reversal of 66828709 is 90782866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58476609 + 8352100 = 7647^2 + 2890^2 .

It is a cyclic number.

It is not a de Polignac number, because 66828709 - 2⁵ = 66828677 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66828739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33414354 + 33414355.

It is an arithmetic number, because the mean of its divisors is an integer number (33414355).

Almost surely, 2^66828709 is an apocalyptic number.

It is an amenable number.

66828709 is a deficient number, since it is larger than the sum of its proper divisors (1).

66828709 is an equidigital number, since it uses as much as digits as its factorization.

66828709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 290304, while the sum is 46.

The square root of 66828709 is about 8174.8828126157. The cubic root of 66828709 is about 405.8083919569.

The spelling of 66828709 in words is "sixty-six million, eight hundred twenty-eight thousand, seven hundred nine".