66817213 has 2 divisors, whose sum is σ = 66817214. Its totient is φ = 66817212.

The previous prime is 66817211. The next prime is 66817237. The reversal of 66817213 is 31271866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 36324729 + 30492484 = 6027^2 + 5522^2 .

It is a cyclic number.

It is not a de Polignac number, because 66817213 - 2¹ = 66817211 is a prime.

Together with 66817211, it forms a pair of twin primes.

It is equal to p_3941638 and since 66817213 and 3941638 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66817211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33408606 + 33408607.

It is an arithmetic number, because the mean of its divisors is an integer number (33408607).

Almost surely, 2^66817213 is an apocalyptic number.

It is an amenable number.

66817213 is a deficient number, since it is larger than the sum of its proper divisors (1).

66817213 is an equidigital number, since it uses as much as digits as its factorization.

66817213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 34.

The square root of 66817213 is about 8174.1796530294. The cubic root of 66817213 is about 405.7851213153.

The spelling of 66817213 in words is "sixty-six million, eight hundred seventeen thousand, two hundred thirteen".