2181680640 has 360 divisors, whose sum is σ = 7942694760. Its totient is φ = 553377792.

The previous prime is 2181680629. The next prime is 2181680659. The reversal of 2181680640 is 460861812.

2181680640 is a `hidden beast` number, since 2 + 1 + 8 + 1 + 6 + 8 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

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

It is a junction number, because it is equal to n+sod(n) for n = 2181680595 and 2181680604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 12188071 + ... + 12188249.

It is an arithmetic number, because the mean of its divisors is an integer number (22063041).

Almost surely, 2^2181680640 is an apocalyptic number.

2181680640 is a gapful number since it is divisible by the number (20) 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 2181680640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3971347380).

2181680640 is an abundant number, since it is smaller than the sum of its proper divisors (5761014120).

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

2181680640 is a wasteful number, since it uses less digits than its factorization.

2181680640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254 (or 212 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 2181680640 is about 46708.4643292840. The cubic root of 2181680640 is about 1296.9713796587.

The spelling of 2181680640 in words is "two billion, one hundred eighty-one million, six hundred eighty thousand, six hundred forty".