681311640 has 64 divisors (see below), whose sum is σ = 2052943200. Its totient is φ = 180882432.

The previous prime is 681311621. The next prime is 681311749. The reversal of 681311640 is 46113186.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 681311598 and 681311607.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15084 + ... + 39876.

Almost surely, 2^681311640 is an apocalyptic number.

681311640 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 681311640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1026471600).

681311640 is an abundant number, since it is smaller than the sum of its proper divisors (1371631560).

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

681311640 is a wasteful number, since it uses less digits than its factorization.

681311640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25036 (or 25032 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 681311640 is about 26101.9470538119. The cubic root of 681311640 is about 879.9309691030.

The spelling of 681311640 in words is "six hundred eighty-one million, three hundred eleven thousand, six hundred forty".