6561581 has 8 divisors (see below), whose sum is σ = 7086240. Its totient is φ = 6039792.

The previous prime is 6561557. The next prime is 6561589. The reversal of 6561581 is 1851656.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6561581 - 2¹⁴ = 6545197 is a prime.

It is a super-2 number, since 2×6561581² = 86108690439122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561589) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8510 + ... + 9248.

It is an arithmetic number, because the mean of its divisors is an integer number (885780).

Almost surely, 2^6561581 is an apocalyptic number.

It is an amenable number.

6561581 is a deficient number, since it is larger than the sum of its proper divisors (524659).

6561581 is a wasteful number, since it uses less digits than its factorization.

6561581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1435.

The product of its digits is 7200, while the sum is 32.

The square root of 6561581 is about 2561.5583147764. The cubic root of 6561581 is about 187.2130698773.

The spelling of 6561581 in words is "six million, five hundred sixty-one thousand, five hundred eighty-one".