66677813 has 2 divisors, whose sum is σ = 66677814. Its totient is φ = 66677812.

The previous prime is 66677789. The next prime is 66677827. The reversal of 66677813 is 31877666.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46812964 + 19864849 = 6842^2 + 4457^2 .

It is a cyclic number.

It is not a de Polignac number, because 66677813 - 2⁸ = 66677557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66677113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33338906 + 33338907.

It is an arithmetic number, because the mean of its divisors is an integer number (33338907).

Almost surely, 2^66677813 is an apocalyptic number.

It is an amenable number.

66677813 is a deficient number, since it is larger than the sum of its proper divisors (1).

66677813 is an equidigital number, since it uses as much as digits as its factorization.

66677813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 254016, while the sum is 44.

The square root of 66677813 is about 8165.6483514783. The cubic root of 66677813 is about 405.5027298625.

The spelling of 66677813 in words is "sixty-six million, six hundred seventy-seven thousand, eight hundred thirteen".