1665980582521 has 2 divisors, whose sum is σ = 1665980582522. Its totient is φ = 1665980582520.

The previous prime is 1665980582509. The next prime is 1665980582653. The reversal of 1665980582521 is 1252850895661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1651646506896 + 14334075625 = 1285164^2 + 119725^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665980582521 - 2⁹ = 1665980582009 is a prime.

It is not a weakly prime, because it can be changed into another prime (1665980582501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832990291260 + 832990291261.

It is an arithmetic number, because the mean of its divisors is an integer number (832990291261).

Almost surely, 2^{1665980582521} is an apocalyptic number.

It is an amenable number.

1665980582521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665980582521 is an equidigital number, since it uses as much as digits as its factorization.

1665980582521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368000, while the sum is 58.

The spelling of 1665980582521 in words is "one trillion, six hundred sixty-five billion, nine hundred eighty million, five hundred eighty-two thousand, five hundred twenty-one".