15665989 has 2 divisors, whose sum is σ = 15665990. Its totient is φ = 15665988.

The previous prime is 15665987. The next prime is 15665999. The reversal of 15665989 is 98956651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15665764 + 225 = 3958^2 + 15^2 .

It is an emirp because it is prime and its reverse (98956651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15665989 - 2¹ = 15665987 is a prime.

It is a super-2 number, since 2×15665989² = 490846422696242, which contains 22 as substring.

Together with 15665987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15665983) 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, 7832994 + 7832995.

It is an arithmetic number, because the mean of its divisors is an integer number (7832995).

Almost surely, 2^15665989 is an apocalyptic number.

It is an amenable number.

15665989 is a deficient number, since it is larger than the sum of its proper divisors (1).

15665989 is an equidigital number, since it uses as much as digits as its factorization.

15665989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 583200, while the sum is 49.

The square root of 15665989 is about 3958.0284233441. The cubic root of 15665989 is about 250.2184171203.

The spelling of 15665989 in words is "fifteen million, six hundred sixty-five thousand, nine hundred eighty-nine".