66397813 has 2 divisors, whose sum is σ = 66397814. Its totient is φ = 66397812.

The previous prime is 66397787. The next prime is 66397843. The reversal of 66397813 is 31879366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61826769 + 4571044 = 7863^2 + 2138^2 .

It is a cyclic number.

It is not a de Polignac number, because 66397813 - 2⁹ = 66397301 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66397813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66397843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33198906 + 33198907.

It is an arithmetic number, because the mean of its divisors is an integer number (33198907).

Almost surely, 2^66397813 is an apocalyptic number.

It is an amenable number.

66397813 is a deficient number, since it is larger than the sum of its proper divisors (1).

66397813 is an equidigital number, since it uses as much as digits as its factorization.

66397813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 43.

The square root of 66397813 is about 8148.4853193707. The cubic root of 66397813 is about 404.9343245637.

The spelling of 66397813 in words is "sixty-six million, three hundred ninety-seven thousand, eight hundred thirteen".