66613709 has 2 divisors, whose sum is σ = 66613710. Its totient is φ = 66613708.

The previous prime is 66613693. The next prime is 66613717. The reversal of 66613709 is 90731666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66373609 + 240100 = 8147^2 + 490^2 .

It is a cyclic number.

It is not a de Polignac number, because 66613709 - 2⁴ = 66613693 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66613759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33306854 + 33306855.

It is an arithmetic number, because the mean of its divisors is an integer number (33306855).

Almost surely, 2^66613709 is an apocalyptic number.

It is an amenable number.

66613709 is a deficient number, since it is larger than the sum of its proper divisors (1).

66613709 is an equidigital number, since it uses as much as digits as its factorization.

66613709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 38.

The square root of 66613709 is about 8161.7221834610. The cubic root of 66613709 is about 405.3727381877.

The spelling of 66613709 in words is "sixty-six million, six hundred thirteen thousand, seven hundred nine".