6561001 has 2 divisors, whose sum is σ = 6561002. Its totient is φ = 6561000.

The previous prime is 6560999. The next prime is 6561007. The reversal of 6561001 is 1001656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4161600 + 2399401 = 2040^2 + 1549^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561001 - 2¹ = 6560999 is a prime.

Together with 6560999, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 6561001.

It is not a weakly prime, because it can be changed into another prime (6561007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280500 + 3280501.

It is an arithmetic number, because the mean of its divisors is an integer number (3280501).

Almost surely, 2^6561001 is an apocalyptic number.

It is an amenable number.

6561001 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561001 is an equidigital number, since it uses as much as digits as its factorization.

6561001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 6561001 is about 2561.4450999387. The cubic root of 6561001 is about 187.2075535858.

Adding to 6561001 its reverse (1001656), we get a palindrome (7562657).

It can be divided in two parts, 656 and 1001, that multiplied together give a palindrome (656656).

The spelling of 6561001 in words is "six million, five hundred sixty-one thousand, one".