664993720669 has 2 divisors, whose sum is σ = 664993720670. Its totient is φ = 664993720668.

The previous prime is 664993720663. The next prime is 664993720673. The reversal of 664993720669 is 966027399466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 620203500900 + 44790219769 = 787530^2 + 211637^2 .

It is a cyclic number.

It is not a de Polignac number, because 664993720669 - 2²⁹ = 664456849757 is a prime.

It is a super-2 number, since 2×664993720669² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664993720663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332496860334 + 332496860335.

It is an arithmetic number, because the mean of its divisors is an integer number (332496860335).

Almost surely, 2^664993720669 is an apocalyptic number.

It is an amenable number.

664993720669 is a deficient number, since it is larger than the sum of its proper divisors (1).

664993720669 is an equidigital number, since it uses as much as digits as its factorization.

664993720669 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 158723712, while the sum is 67.

The spelling of 664993720669 in words is "six hundred sixty-four billion, nine hundred ninety-three million, seven hundred twenty thousand, six hundred sixty-nine".