581581 has 24 divisors (see below), whose sum is σ = 804384. Its totient is φ = 413280.

The previous prime is 581573. The next prime is 581597. The reversal of 581581 is 185185.

581581 is nontrivially palindromic in base 9.

581581 is a nontrivial binomial coefficient, being equal to C(1079, 2).

It is not a de Polignac number, because 581581 - 2³ = 581573 is a prime.

It is a super-2 number, since 2×581581² = 676472919122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (581521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6966 + ... + 7048.

It is an arithmetic number, because the mean of its divisors is an integer number (33516).

2⁵⁸¹⁵⁸¹ is an apocalyptic number.

581581 is the 1078-th triangular number.

581581 is the 360-th centered nonagonal number.

It is an amenable number.

581581 is a deficient number, since it is larger than the sum of its proper divisors (222803).

581581 is a wasteful number, since it uses less digits than its factorization.

581581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121 (or 114 counting only the distinct ones).

The product of its digits is 1600, while the sum is 28.

The square root of 581581 is about 762.6145815548. The cubic root of 581581 is about 83.4712152925.

The spelling of 581581 in words is "five hundred eighty-one thousand, five hundred eighty-one".