68784521 has 12 divisors (see below), whose sum is σ = 74758428. Its totient is φ = 63258624.

The previous prime is 68784481. The next prime is 68784571. The reversal of 68784521 is 12548786.

68784521 = 1614² + 1615² + ... + 1639².

It can be written as a sum of positive squares in 6 ways, for example, as 5359225 + 63425296 = 2315^2 + 7964^2 .

It is a de Polignac number, because none of the positive numbers 2^k-68784521 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68784571) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59081 + ... + 60233.

It is an arithmetic number, because the mean of its divisors is an integer number (6229869).

Almost surely, 2^68784521 is an apocalyptic number.

It is an amenable number.

68784521 is a deficient number, since it is larger than the sum of its proper divisors (5973907).

68784521 is a wasteful number, since it uses less digits than its factorization.

68784521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1532 (or 1519 counting only the distinct ones).

The product of its digits is 107520, while the sum is 41.

The square root of 68784521 is about 8293.6434092623. The cubic root of 68784521 is about 409.7291905898.

The spelling of 68784521 in words is "sixty-eight million, seven hundred eighty-four thousand, five hundred twenty-one".