2001166520 has 128 divisors (see below), whose sum is σ = 4833561600. Its totient is φ = 743998464.

The previous prime is 2001166501. The next prime is 2001166523. The reversal of 2001166520 is 256611002.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001166523) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5574101 + ... + 5574459.

It is an arithmetic number, because the mean of its divisors is an integer number (37762200).

Almost surely, 2^2001166520 is an apocalyptic number.

2001166520 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 2001166520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2416780800).

2001166520 is an abundant number, since it is smaller than the sum of its proper divisors (2832395080).

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

2001166520 is a wasteful number, since it uses less digits than its factorization.

2001166520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549 (or 545 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 2001166520 is about 44734.3997389034. The cubic root of 2001166520 is about 1260.1659561369.

Adding to 2001166520 its reverse (256611002), we get a palindrome (2257777522).

The spelling of 2001166520 in words is "two billion, one million, one hundred sixty-six thousand, five hundred twenty".