2001156660 has 72 divisors (see below), whose sum is σ = 6102061056. Its totient is φ = 530838720.

The previous prime is 2001156613. The next prime is 2001156673. The reversal of 2001156660 is 666511002.

It is a happy number.

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 23 ways as a sum of consecutive naturals, for example, 5277 + ... + 63483.

It is an arithmetic number, because the mean of its divisors is an integer number (84750848).

Almost surely, 2^2001156660 is an apocalyptic number.

2001156660 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 2001156660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3051030528).

2001156660 is an abundant number, since it is smaller than the sum of its proper divisors (4100904396).

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

2001156660 is a wasteful number, since it uses less digits than its factorization.

2001156660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58413 (or 58408 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 2001156660 is about 44734.2895327510. The cubic root of 2001156660 is about 1260.1638864679.

Adding to 2001156660 its reverse (666511002), we get a palindrome (2667667662).

The spelling of 2001156660 in words is "two billion, one million, one hundred fifty-six thousand, six hundred sixty".