681518656 has 168 divisors, whose sum is σ = 1724908920. Its totient is φ = 264757248.

The previous prime is 681518639. The next prime is 681518711. The reversal of 681518656 is 656815186.

It can be written as a sum of positive squares in 4 ways, for example, as 151782400 + 529736256 = 12320^2 + 23016^2 .

It is a super-3 number, since 3×681518656³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2975950 + ... + 2976178.

It is an arithmetic number, because the mean of its divisors is an integer number (10267315).

Almost surely, 2^681518656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681518656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (862454460).

681518656 is an abundant number, since it is smaller than the sum of its proper divisors (1043390264).

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

681518656 is a wasteful number, since it uses less digits than its factorization.

681518656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341 (or 324 counting only the distinct ones).

The product of its digits is 345600, while the sum is 46.

The square root of 681518656 is about 26105.9122805544. The cubic root of 681518656 is about 880.0200821863.

The spelling of 681518656 in words is "six hundred eighty-one million, five hundred eighteen thousand, six hundred fifty-six".