2011581 has 32 divisors (see below), whose sum is σ = 3507840. Its totient is φ = 1123200.

The previous prime is 2011573. The next prime is 2011591. The reversal of 2011581 is 1851102.

It is not a de Polignac number, because 2011581 - 2³ = 2011573 is a prime.

It is a super-2 number, since 2×2011581² = 8092916239122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2011531) 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, 3601 + ... + 4121.

It is an arithmetic number, because the mean of its divisors is an integer number (109620).

2^2011581 is an apocalyptic number.

It is an amenable number.

2011581 is a deficient number, since it is larger than the sum of its proper divisors (1496259).

2011581 is a wasteful number, since it uses less digits than its factorization.

2011581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 554 (or 548 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 2011581 is about 1418.3021539855. The cubic root of 2011581 is about 126.2348228659.

Adding to 2011581 its reverse (1851102), we get a palindrome (3862683).

The spelling of 2011581 in words is "two million, eleven thousand, five hundred eighty-one".