1686203534521 has 27 divisors (see below), whose sum is σ = 1874274922317. Its totient is φ = 1515862487040.

The previous prime is 1686203534467. The next prime is 1686203534527. The reversal of 1686203534521 is 1254353026861.

It is a happy number.

The square root of 1686203534521 is 1298539.

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

It can be written as a sum of positive squares in 4 ways, for example, as 79292364921 + 1606911169600 = 281589^2 + 1267640^2 .

It is not a de Polignac number, because 1686203534521 - 2²⁹ = 1685666663609 is a prime.

It is a super-2 number, since 2×1686203534521² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1686203534527) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1385540505 + ... + 1385541721.

Almost surely, 2^{1686203534521} is an apocalyptic number.

1686203534521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1686203534521 is the 1298539-th square number.

1686203534521 is the 649270-th centered octagonal number.

It is an amenable number.

1686203534521 is a deficient number, since it is larger than the sum of its proper divisors (188071387796).

1686203534521 is an frugal number, since it uses more digits than its factorization.

1686203534521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2650 (or 1325 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 46.

The spelling of 1686203534521 in words is "one trillion, six hundred eighty-six billion, two hundred three million, five hundred thirty-four thousand, five hundred twenty-one".