681781536 has 120 divisors (see below), whose sum is σ = 2059582140. Its totient is φ = 221087232.

The previous prime is 681781531. The next prime is 681781537. The reversal of 681781536 is 635187186.

It can be written as a sum of positive squares in 2 ways, for example, as 681210000 + 571536 = 26100^2 + 756^2 .

It is a junction number, because it is equal to n+sod(n) for n = 681781491 and 681781500.

It is not an unprimeable number, because it can be changed into a prime (681781531) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 92350 + ... + 99458.

Almost surely, 2^681781536 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 681781536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1029791070).

681781536 is an abundant number, since it is smaller than the sum of its proper divisors (1377800604).

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

681781536 is a wasteful number, since it uses less digits than its factorization.

681781536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7168 (or 7151 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The square root of 681781536 is about 26110.9466699314. The cubic root of 681781536 is about 880.1332167469.

The spelling of 681781536 in words is "six hundred eighty-one million, seven hundred eighty-one thousand, five hundred thirty-six".