16556009 has 2 divisors, whose sum is σ = 16556010. Its totient is φ = 16556008.

The previous prime is 16555999. The next prime is 16556017. The reversal of 16556009 is 90065561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15960025 + 595984 = 3995^2 + 772^2 .

It is a cyclic number.

It is not a de Polignac number, because 16556009 - 2⁸ = 16555753 is a prime.

It is not a weakly prime, because it can be changed into another prime (16556069) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8278004 + 8278005.

It is an arithmetic number, because the mean of its divisors is an integer number (8278005).

Almost surely, 2^16556009 is an apocalyptic number.

It is an amenable number.

16556009 is a deficient number, since it is larger than the sum of its proper divisors (1).

16556009 is an equidigital number, since it uses as much as digits as its factorization.

16556009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8100, while the sum is 32.

The square root of 16556009 is about 4068.9075929542. The cubic root of 16556009 is about 254.8699015974.

The spelling of 16556009 in words is "sixteen million, five hundred fifty-six thousand, nine".