681666768 has 30 divisors (see below), whose sum is σ = 1907720594. Its totient is φ = 227222208.

The previous prime is 681666763. The next prime is 681666787. The reversal of 681666768 is 867666186.

It can be written as a sum of positive squares in only one way, i.e., 463454784 + 218211984 = 21528^2 + 14772^2 .

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681666763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2366755 + ... + 2367042.

Almost surely, 2^681666768 is an apocalyptic number.

It is an amenable number.

681666768 is an abundant number, since it is smaller than the sum of its proper divisors (1226053826).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681666768 is a wasteful number, since it uses less digits than its factorization.

681666768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4733811 (or 4733802 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 54.

The square root of 681666768 is about 26108.7488784890. The cubic root of 681666768 is about 880.0838281025.

The spelling of 681666768 in words is "six hundred eighty-one million, six hundred sixty-six thousand, seven hundred sixty-eight".