6664720591 has 2 divisors, whose sum is σ = 6664720592. Its totient is φ = 6664720590.

The previous prime is 6664720577. The next prime is 6664720607. The reversal of 6664720591 is 1950274666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6664720591 - 2¹³ = 6664712399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6664720561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3332360295 + 3332360296.

It is an arithmetic number, because the mean of its divisors is an integer number (3332360296).

Almost surely, 2^6664720591 is an apocalyptic number.

6664720591 is a deficient number, since it is larger than the sum of its proper divisors (1).

6664720591 is an equidigital number, since it uses as much as digits as its factorization.

6664720591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 544320, while the sum is 46.

The square root of 6664720591 is about 81637.7399919914. The cubic root of 6664720591 is about 1881.8889072079. Note that the first 3 decimals are identical.

The spelling of 6664720591 in words is "six billion, six hundred sixty-four million, seven hundred twenty thousand, five hundred ninety-one".