681056640 has 256 divisors, whose sum is σ = 2632089600. Its totient is φ = 165058560.

The previous prime is 681056633. The next prime is 681056683. The reversal of 681056640 is 46650186.

681056640 is a `hidden beast` number, since 6 + 8 + 1 + 0 + 5 + 6 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 681056595 and 681056604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 188289 + ... + 191871.

It is an arithmetic number, because the mean of its divisors is an integer number (10281600).

Almost surely, 2^681056640 is an apocalyptic number.

681056640 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 681056640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1316044800).

681056640 is an abundant number, since it is smaller than the sum of its proper divisors (1951032960).

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

681056640 is a wasteful number, since it uses less digits than its factorization.

681056640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3622 (or 3604 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 681056640 is about 26097.0619035937. The cubic root of 681056640 is about 879.8211757849.

The spelling of 681056640 in words is "six hundred eighty-one million, fifty-six thousand, six hundred forty".