1215664431689 has 2 divisors, whose sum is σ = 1215664431690. Its totient is φ = 1215664431688.

The previous prime is 1215664431673. The next prime is 1215664431691. The reversal of 1215664431689 is 9861344665121.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 783216150025 + 432448281664 = 884995^2 + 657608^2 .

It is an emirp because it is prime and its reverse (9861344665121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1215664431689 - 2⁴ = 1215664431673 is a prime.

Together with 1215664431691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1215664431629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607832215844 + 607832215845.

It is an arithmetic number, because the mean of its divisors is an integer number (607832215845).

Almost surely, 2^{1215664431689} is an apocalyptic number.

It is an amenable number.

1215664431689 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215664431689 is an equidigital number, since it uses as much as digits as its factorization.

1215664431689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7464960, while the sum is 56.

The spelling of 1215664431689 in words is "one trillion, two hundred fifteen billion, six hundred sixty-four million, four hundred thirty-one thousand, six hundred eighty-nine".