667504361672021 has 2 divisors, whose sum is σ = 667504361672022. Its totient is φ = 667504361672020.

The previous prime is 667504361671999. The next prime is 667504361672047. The reversal of 667504361672021 is 120276163405766.

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., 666803313826225 + 701047845796 = 25822535^2 + 837286^2 .

It is a cyclic number.

It is not a de Polignac number, because 667504361672021 - 2⁴⁶ = 597135617494357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667504361672051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333752180836010 + 333752180836011.

It is an arithmetic number, because the mean of its divisors is an integer number (333752180836011).

Almost surely, 2^{667504361672021} is an apocalyptic number.

It is an amenable number.

667504361672021 is a deficient number, since it is larger than the sum of its proper divisors (1).

667504361672021 is an equidigital number, since it uses as much as digits as its factorization.

667504361672021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15240960, while the sum is 56.

The spelling of 667504361672021 in words is "six hundred sixty-seven trillion, five hundred four billion, three hundred sixty-one million, six hundred seventy-two thousand, twenty-one".