840666681 has 20 divisors (see below), whose sum is σ = 1276405284. Its totient is φ = 551253600.

The previous prime is 840666667. The next prime is 840666683. The reversal of 840666681 is 186666048.

840666681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 37454400 + 803212281 = 6120^2 + 28341^2 .

It is not a de Polignac number, because 840666681 - 2¹⁷ = 840535609 is a prime.

It is a super-2 number, since 2×840666681² = 1413440937087111522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (840666683) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 80130 + ... + 90011.

Almost surely, 2^840666681 is an apocalyptic number.

840666681 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

840666681 is a deficient number, since it is larger than the sum of its proper divisors (435738603).

840666681 is a wasteful number, since it uses less digits than its factorization.

840666681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170214 (or 170205 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The square root of 840666681 is about 28994.2525511523. The cubic root of 840666681 is about 943.7883488591.

The spelling of 840666681 in words is "eight hundred forty million, six hundred sixty-six thousand, six hundred eighty-one".