6641581 has 4 divisors (see below), whose sum is σ = 6656572. Its totient is φ = 6626592.

The previous prime is 6641573. The next prime is 6641587. The reversal of 6641581 is 1851466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1851466 = 2 ⋅925733.

It can be written as a sum of positive squares in 2 ways, for example, as 4862025 + 1779556 = 2205^2 + 1334^2 .

It is a cyclic number.

It is not a de Polignac number, because 6641581 - 2³ = 6641573 is a prime.

It is a super-2 number, since 2×6641581² = 88221196359122, 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 (6641587) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6810 + ... + 7723.

It is an arithmetic number, because the mean of its divisors is an integer number (1664143).

Almost surely, 2^6641581 is an apocalyptic number.

It is an amenable number.

6641581 is a deficient number, since it is larger than the sum of its proper divisors (14991).

6641581 is a wasteful number, since it uses less digits than its factorization.

6641581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14990.

The product of its digits is 5760, while the sum is 31.

The square root of 6641581 is about 2577.1265005816. The cubic root of 6641581 is about 187.9708439017.

The spelling of 6641581 in words is "six million, six hundred forty-one thousand, five hundred eighty-one".