2181201660 has 432 divisors, whose sum is σ = 7936856928. Its totient is φ = 482549760.

The previous prime is 2181201647. The next prime is 2181201661. The reversal of 2181201660 is 661021812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181201661) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 15921112 + ... + 15921248.

It is an arithmetic number, because the mean of its divisors is an integer number (18372354).

Almost surely, 2^2181201660 is an apocalyptic number.

2181201660 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 2181201660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3968428464).

2181201660 is an abundant number, since it is smaller than the sum of its proper divisors (5755655268).

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

2181201660 is a wasteful number, since it uses less digits than its factorization.

2181201660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234 (or 218 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 2181201660 is about 46703.3367116312. The cubic root of 2181201660 is about 1296.8764576052.

It can be divided in two parts, 2181 and 201660, that added together give a triangular number (203841 = T₆₃₈).

The spelling of 2181201660 in words is "two billion, one hundred eighty-one million, two hundred one thousand, six hundred sixty".