15681689 has 2 divisors, whose sum is σ = 15681690. Its totient is φ = 15681688.

The previous prime is 15681683. The next prime is 15681703. The reversal of 15681689 is 98618651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12369289 + 3312400 = 3517^2 + 1820^2 .

It is a cyclic number.

It is not a de Polignac number, because 15681689 - 2¹² = 15677593 is a prime.

It is not a weakly prime, because it can be changed into another prime (15681683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7840844 + 7840845.

It is an arithmetic number, because the mean of its divisors is an integer number (7840845).

Almost surely, 2^15681689 is an apocalyptic number.

It is an amenable number.

15681689 is a deficient number, since it is larger than the sum of its proper divisors (1).

15681689 is an equidigital number, since it uses as much as digits as its factorization.

15681689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 44.

The square root of 15681689 is about 3960.0112373578. The cubic root of 15681689 is about 250.3019764274.

The spelling of 15681689 in words is "fifteen million, six hundred eighty-one thousand, six hundred eighty-nine".