681827661 has 12 divisors (see below), whose sum is σ = 985103392. Its totient is φ = 454440456.

The previous prime is 681827639. The next prime is 681827677. The reversal of 681827661 is 166728186.

It is a happy number.

It is not a de Polignac number, because 681827661 - 2¹⁰ = 681826637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681827611) 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, 48360 + ... + 60846.

Almost surely, 2^681827661 is an apocalyptic number.

It is an amenable number.

681827661 is a deficient number, since it is larger than the sum of its proper divisors (303275731).

681827661 is a wasteful number, since it uses less digits than its factorization.

681827661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18560 (or 18557 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 681827661 is about 26111.8299052364. The cubic root of 681827661 is about 880.1530643701.

The spelling of 681827661 in words is "six hundred eighty-one million, eight hundred twenty-seven thousand, six hundred sixty-one".