16981609 has 2 divisors, whose sum is σ = 16981610. Its totient is φ = 16981608.

The previous prime is 16981577. The next prime is 16981669. The reversal of 16981609 is 90618961.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12981609 + 4000000 = 3603^2 + 2000^2 .

It is a cyclic number.

It is not a de Polignac number, because 16981609 - 2⁵ = 16981577 is a prime.

It is not a weakly prime, because it can be changed into another prime (16981669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8490804 + 8490805.

It is an arithmetic number, because the mean of its divisors is an integer number (8490805).

Almost surely, 2^16981609 is an apocalyptic number.

It is an amenable number.

16981609 is a deficient number, since it is larger than the sum of its proper divisors (1).

16981609 is an equidigital number, since it uses as much as digits as its factorization.

16981609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 16981609 is about 4120.8747857706. The cubic root of 16981609 is about 257.0354031784.

The spelling of 16981609 in words is "sixteen million, nine hundred eighty-one thousand, six hundred nine".