667615375215521 has 2 divisors, whose sum is σ = 667615375215522. Its totient is φ = 667615375215520.

The previous prime is 667615375215463. The next prime is 667615375215589. The reversal of 667615375215521 is 125512573516766.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 344627479581025 + 322987895634496 = 18564145^2 + 17971864^2 .

It is a cyclic number.

It is not a de Polignac number, because 667615375215521 - 2³⁸ = 667340497308577 is a prime.

It is not a weakly prime, because it can be changed into another prime (667615375214521) 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, 333807687607760 + 333807687607761.

It is an arithmetic number, because the mean of its divisors is an integer number (333807687607761).

Almost surely, 2^{667615375215521} is an apocalyptic number.

It is an amenable number.

667615375215521 is a deficient number, since it is larger than the sum of its proper divisors (1).

667615375215521 is an equidigital number, since it uses as much as digits as its factorization.

667615375215521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 79380000, while the sum is 62.

The spelling of 667615375215521 in words is "six hundred sixty-seven trillion, six hundred fifteen billion, three hundred seventy-five million, two hundred fifteen thousand, five hundred twenty-one".