667443161621 has 2 divisors, whose sum is σ = 667443161622. Its totient is φ = 667443161620.

The previous prime is 667443161591. The next prime is 667443161641. The reversal of 667443161621 is 126161344766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 451510083025 + 215933078596 = 671945^2 + 464686^2 .

It is a cyclic number.

It is not a de Polignac number, because 667443161621 - 2¹⁰ = 667443160597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667443161641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333721580810 + 333721580811.

It is an arithmetic number, because the mean of its divisors is an integer number (333721580811).

Almost surely, 2^667443161621 is an apocalyptic number.

It is an amenable number.

667443161621 is a deficient number, since it is larger than the sum of its proper divisors (1).

667443161621 is an equidigital number, since it uses as much as digits as its factorization.

667443161621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 870912, while the sum is 47.

The spelling of 667443161621 in words is "six hundred sixty-seven billion, four hundred forty-three million, one hundred sixty-one thousand, six hundred twenty-one".