665223217 has 2 divisors, whose sum is σ = 665223218. Its totient is φ = 665223216.

The previous prime is 665223197. The next prime is 665223263. The reversal of 665223217 is 712322566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644347456 + 20875761 = 25384^2 + 4569^2 .

It is a cyclic number.

It is not a de Polignac number, because 665223217 - 2²³ = 656834609 is a prime.

It is equal to p_34543465 and since 665223217 and 34543465 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (665227217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332611608 + 332611609.

It is an arithmetic number, because the mean of its divisors is an integer number (332611609).

Almost surely, 2^665223217 is an apocalyptic number.

It is an amenable number.

665223217 is a deficient number, since it is larger than the sum of its proper divisors (1).

665223217 is an equidigital number, since it uses as much as digits as its factorization.

665223217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 34.

The square root of 665223217 is about 25791.9215453211. The cubic root of 665223217 is about 872.9495244364.

The spelling of 665223217 in words is "six hundred sixty-five million, two hundred twenty-three thousand, two hundred seventeen".