681840664380 has 144 divisors (see below), whose sum is σ = 2145349140480. Its totient is φ = 181782024768.

The previous prime is 681840664339. The next prime is 681840664381. The reversal of 681840664380 is 83466048186.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681840664381) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24864637 + ... + 24892043.

It is an arithmetic number, because the mean of its divisors is an integer number (14898257920).

Almost surely, 2^681840664380 is an apocalyptic number.

681840664380 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 681840664380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1072674570240).

681840664380 is an abundant number, since it is smaller than the sum of its proper divisors (1463508476100).

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

681840664380 is a wasteful number, since it uses less digits than its factorization.

681840664380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32550 (or 32536 counting only the distinct ones).

The product of its (nonzero) digits is 5308416, while the sum is 54.

The spelling of 681840664380 in words is "six hundred eighty-one billion, eight hundred forty million, six hundred sixty-four thousand, three hundred eighty".