15865669681 has 3 divisors (see below), whose sum is σ = 15865795641. Its totient is φ = 15865543722.

The previous prime is 15865669669. The next prime is 15865669717. The reversal of 15865669681 is 18696656851.

The square root of 15865669681 is 125959.

It is a perfect power (a square), and thus also a powerful number.

15865669681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 15865669681 - 2⁷ = 15865669553 is a prime.

It is a super-2 number, since 2×15865669681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15865669601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 62980 + ... + 188938.

It is an arithmetic number, because the mean of its divisors is an integer number (5288598547).

Almost surely, 2^15865669681 is an apocalyptic number.

15865669681 is the 125959-th square number.

15865669681 is the 62980-th centered octagonal number.

It is an amenable number.

15865669681 is a deficient number, since it is larger than the sum of its proper divisors (125960).

15865669681 is an frugal number, since it uses more digits than its factorization.

15865669681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251918 (or 125959 counting only the distinct ones).

The product of its digits is 18662400, while the sum is 61.

The spelling of 15865669681 in words is "fifteen billion, eight hundred sixty-five million, six hundred sixty-nine thousand, six hundred eighty-one".