1680786678521 has 8 divisors (see below), whose sum is σ = 1682457518280. Its totient is φ = 1679116025088.

The previous prime is 1680786678509. The next prime is 1680786678553. The reversal of 1680786678521 is 1258766870861.

It can be written as a sum of positive squares in 4 ways, for example, as 2373151225 + 1678413527296 = 48715^2 + 1295536^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1680786678521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1680786648521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24164225 + ... + 24233681.

It is an arithmetic number, because the mean of its divisors is an integer number (210307189785).

Almost surely, 2^{1680786678521} is an apocalyptic number.

It is an amenable number.

1680786678521 is a deficient number, since it is larger than the sum of its proper divisors (1670839759).

1680786678521 is a wasteful number, since it uses less digits than its factorization.

1680786678521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93163.

The product of its (nonzero) digits is 54190080, while the sum is 65.

The spelling of 1680786678521 in words is "one trillion, six hundred eighty billion, seven hundred eighty-six million, six hundred seventy-eight thousand, five hundred twenty-one".