6561643 has 8 divisors (see below), whose sum is σ = 7579440. Its totient is φ = 5614080.

The previous prime is 6561637. The next prime is 6561649. The reversal of 6561643 is 3461656.

It is an interprime number because it is at equal distance from previous prime (6561637) and next prime (6561649).

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

It is not a de Polignac number, because 6561643 - 2¹³ = 6553451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6561649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17358 + ... + 17731.

It is an arithmetic number, because the mean of its divisors is an integer number (947430).

Almost surely, 2^6561643 is an apocalyptic number.

6561643 is a deficient number, since it is larger than the sum of its proper divisors (1017797).

6561643 is a wasteful number, since it uses less digits than its factorization.

6561643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35117.

The product of its digits is 12960, while the sum is 31.

The square root of 6561643 is about 2561.5704167561. The cubic root of 6561643 is about 187.2136595306.

The spelling of 6561643 in words is "six million, five hundred sixty-one thousand, six hundred forty-three".