15681389 has 2 divisors, whose sum is σ = 15681390. Its totient is φ = 15681388.

The previous prime is 15681383. The next prime is 15681401. The reversal of 15681389 is 98318651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15665764 + 15625 = 3958^2 + 125^2 .

It is an emirp because it is prime and its reverse (98318651) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15681389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15681383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7840694 + 7840695.

It is an arithmetic number, because the mean of its divisors is an integer number (7840695).

Almost surely, 2^15681389 is an apocalyptic number.

It is an amenable number.

15681389 is a deficient number, since it is larger than the sum of its proper divisors (1).

15681389 is an equidigital number, since it uses as much as digits as its factorization.

15681389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 41.

The square root of 15681389 is about 3959.9733584962. The cubic root of 15681389 is about 250.3003802755.

The spelling of 15681389 in words is "fifteen million, six hundred eighty-one thousand, three hundred eighty-nine".