6581 has 2 divisors, whose sum is σ = 6582. Its totient is φ = 6580.

The previous prime is 6577. The next prime is 6599. The reversal of 6581 is 1856.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4900 + 1681 = 70^2 + 41^2 .

It is a cyclic number.

It is not a de Polignac number, because 6581 - 2² = 6577 is a prime.

It is a super-2 number, since 2×6581² = 86619122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

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 6581.

It is not a weakly prime, because it can be changed into another prime (6521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3290 + 3291.

It is an arithmetic number, because the mean of its divisors is an integer number (3291).

2⁶⁵⁸¹ is an apocalyptic number.

It is an amenable number.

6581 is a deficient number, since it is larger than the sum of its proper divisors (1).

6581 is an equidigital number, since it uses as much as digits as its factorization.

6581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 240, while the sum is 20.

The square root of 6581 is about 81.1233628494. The cubic root of 6581 is about 18.7397573687.

Subtracting from 6581 its sum of digits (20), we obtain a 8-th power (6561 = 3⁸).

It can be divided in two parts, 6 and 581, that multiplied together give a triangular number (3486 = T₈₃).

The spelling of 6581 in words is "six thousand, five hundred eighty-one".