1591688645521 has 12 divisors (see below), whose sum is σ = 1765582188300. Its totient is φ = 1433415659520.

The previous prime is 1591688645507. The next prime is 1591688645549. The reversal of 1591688645521 is 1255468861951.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 1000080001600 + 591608643921 = 1000040^2 + 769161^2 .

It is not a de Polignac number, because 1591688645521 - 2¹¹ = 1591688643473 is a prime.

It is a super-2 number, since 2×1591688645521² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1591688645521.

It is not an unprimeable number, because it can be changed into a prime (1591688645551) 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 11 ways as a sum of consecutive naturals, for example, 114850096 + ... + 114863953.

It is an arithmetic number, because the mean of its divisors is an integer number (147131849025).

Almost surely, 2^{1591688645521} is an apocalyptic number.

It is an amenable number.

1591688645521 is a deficient number, since it is larger than the sum of its proper divisors (173893542779).

1591688645521 is a wasteful number, since it uses less digits than its factorization.

1591688645521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229714116 (or 229714103 counting only the distinct ones).

The product of its digits is 20736000, while the sum is 61.

The spelling of 1591688645521 in words is "one trillion, five hundred ninety-one billion, six hundred eighty-eight million, six hundred forty-five thousand, five hundred twenty-one".