16581644917 has 2 divisors, whose sum is σ = 16581644918. Its totient is φ = 16581644916.

The previous prime is 16581644903. The next prime is 16581644923. The reversal of 16581644917 is 71944618561.

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., 15753011121 + 828633796 = 125511^2 + 28786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16581644917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16581644927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8290822458 + 8290822459.

It is an arithmetic number, because the mean of its divisors is an integer number (8290822459).

Almost surely, 2^16581644917 is an apocalyptic number.

It is an amenable number.

16581644917 is a deficient number, since it is larger than the sum of its proper divisors (1).

16581644917 is an equidigital number, since it uses as much as digits as its factorization.

16581644917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1451520, while the sum is 52.

The spelling of 16581644917 in words is "sixteen billion, five hundred eighty-one million, six hundred forty-four thousand, nine hundred seventeen".