16680581221 has 2 divisors, whose sum is σ = 16680581222. Its totient is φ = 16680581220.

The previous prime is 16680581209. The next prime is 16680581227. The reversal of 16680581221 is 12218508661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12152637121 + 4527944100 = 110239^2 + 67290^2 .

It is a cyclic number.

It is not a de Polignac number, because 16680581221 - 2²⁵ = 16647026789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16680581227) 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, 8340290610 + 8340290611.

It is an arithmetic number, because the mean of its divisors is an integer number (8340290611).

Almost surely, 2^16680581221 is an apocalyptic number.

It is an amenable number.

16680581221 is a deficient number, since it is larger than the sum of its proper divisors (1).

16680581221 is an equidigital number, since it uses as much as digits as its factorization.

16680581221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46080, while the sum is 40.

The spelling of 16680581221 in words is "sixteen billion, six hundred eighty million, five hundred eighty-one thousand, two hundred twenty-one".