681655860 has 72 divisors (see below), whose sum is σ = 2089059336. Its totient is φ = 179896320.

The previous prime is 681655841. The next prime is 681655867. The reversal of 681655860 is 68556186.

681655860 is a `hidden beast` number, since 6 + 8 + 1 + 65 + 586 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 193599396 + 488056464 = 13914^2 + 22092^2 .

It is a super-2 number, since 2×681655860² = 929309422944679200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681655867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2061 + ... + 36980.

It is an arithmetic number, because the mean of its divisors is an integer number (29014713).

Almost surely, 2^681655860 is an apocalyptic number.

681655860 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681655860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1044529668).

681655860 is an abundant number, since it is smaller than the sum of its proper divisors (1407403476).

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

681655860 is a wasteful number, since it uses less digits than its factorization.

681655860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39153 (or 39148 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The square root of 681655860 is about 26108.5399821591. The cubic root of 681655860 is about 880.0791337239.

The spelling of 681655860 in words is "six hundred eighty-one million, six hundred fifty-five thousand, eight hundred sixty".