6656581 has 4 divisors (see below), whose sum is σ = 6721312. Its totient is φ = 6591852.

The previous prime is 6656569. The next prime is 6656597. The reversal of 6656581 is 1856566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6656581 - 2⁵ = 6656549 is a prime.

It is a super-2 number, since 2×6656581² = 88620141219122, which contains 22 as substring.

It is a Duffinian number.

6656581 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 6656581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6656561) 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, 32211 + ... + 32416.

It is an arithmetic number, because the mean of its divisors is an integer number (1680328).

Almost surely, 2^6656581 is an apocalyptic number.

It is an amenable number.

6656581 is a deficient number, since it is larger than the sum of its proper divisors (64731).

6656581 is a wasteful number, since it uses less digits than its factorization.

6656581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64730.

The product of its digits is 43200, while the sum is 37.

The square root of 6656581 is about 2580.0350772809. The cubic root of 6656581 is about 188.1122481174.

The spelling of 6656581 in words is "six million, six hundred fifty-six thousand, five hundred eighty-one".