3581 has 2 divisors, whose sum is σ = 3582. Its totient is φ = 3580.

The previous prime is 3571. The next prime is 3583. The reversal of 3581 is 1853.

3581 is nontrivially palindromic in base 16.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3481 + 100 = 59^2 + 10^2 .

It is a cyclic number.

It is not a de Polignac number, because 3581 - 2⁶ = 3517 is a prime.

It is a super-2 number, since 2×3581² = 25647122, which contains 22 as substring.

Together with 3583, it forms a pair of twin primes.

It is a Chen prime.

3581 is an undulating number in base 16.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 3581.

It is not a weakly prime, because it can be changed into another prime (3583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1790 + 1791.

It is an arithmetic number, because the mean of its divisors is an integer number (1791).

2³⁵⁸¹ is an apocalyptic number.

It is an amenable number.

3581 is a deficient number, since it is larger than the sum of its proper divisors (1).

3581 is an equidigital number, since it uses as much as digits as its factorization.

3581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120, while the sum is 17.

The square root of 3581 is about 59.8414572015. The cubic root of 3581 is about 15.2991783346.

Subtracting from 3581 its reverse (1853), we obtain a cube (1728 = 12³).

The spelling of 3581 in words is "three thousand, five hundred eighty-one".