681815520 has 216 divisors, whose sum is σ = 2413973016. Its totient is φ = 175236096.

The previous prime is 681815509. The next prime is 681815521. The reversal of 681815520 is 25518186.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681815521) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1210759 + ... + 1211321.

It is an arithmetic number, because the mean of its divisors is an integer number (11175801).

Almost surely, 2^681815520 is an apocalyptic number.

681815520 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 681815520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1206986508).

681815520 is an abundant number, since it is smaller than the sum of its proper divisors (1732157496).

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

681815520 is a wasteful number, since it uses less digits than its factorization.

681815520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642 (or 602 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 36.

The square root of 681815520 is about 26111.5974233673. The cubic root of 681815520 is about 880.1478401752.

The spelling of 681815520 in words is "six hundred eighty-one million, eight hundred fifteen thousand, five hundred twenty".