861645680 has 160 divisors (see below), whose sum is σ = 2508589440. Its totient is φ = 268369920.

The previous prime is 861645667. The next prime is 861645683. The reversal of 861645680 is 86546168.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861645683) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 274520 + ... + 277640.

It is an arithmetic number, because the mean of its divisors is an integer number (15678684).

Almost surely, 2^861645680 is an apocalyptic number.

861645680 is a gapful number since it is divisible by the number (80) 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 861645680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1254294720).

861645680 is an abundant number, since it is smaller than the sum of its proper divisors (1646943760).

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

861645680 is a wasteful number, since it uses less digits than its factorization.

861645680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3187 (or 3181 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 44.

The square root of 861645680 is about 29353.8017980636. The cubic root of 861645680 is about 951.5747400359.

The spelling of 861645680 in words is "eight hundred sixty-one million, six hundred forty-five thousand, six hundred eighty".