6561647 has 4 divisors (see below), whose sum is σ = 6846960. Its totient is φ = 6276336.

The previous prime is 6561637. The next prime is 6561649. The reversal of 6561647 is 7461656.

6561647 is nontrivially palindromic in base 13.

6561647 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6561647 is a prime.

It is a super-2 number, since 2×6561647² = 86110422705218, 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 (6561649) 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, 142622 + ... + 142667.

It is an arithmetic number, because the mean of its divisors is an integer number (1711740).

Almost surely, 2^6561647 is an apocalyptic number.

6561647 is a deficient number, since it is larger than the sum of its proper divisors (285313).

6561647 is a wasteful number, since it uses less digits than its factorization.

6561647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285312.

The product of its digits is 30240, while the sum is 35.

The square root of 6561647 is about 2561.5711975270. The cubic root of 6561647 is about 187.2136975726.

Subtracting 6561647 from its reverse (7461656), we obtain a palindrome (900009).

The spelling of 6561647 in words is "six million, five hundred sixty-one thousand, six hundred forty-seven".