6561021 has 8 divisors (see below), whose sum is σ = 8868160. Its totient is φ = 4313952.

The previous prime is 6561019. The next prime is 6561073. The reversal of 6561021 is 1201656.

It is a happy number.

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

It is not a de Polignac number, because 6561021 - 2¹ = 6561019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561001) 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, 14761 + ... + 15198.

It is an arithmetic number, because the mean of its divisors is an integer number (1108520).

Almost surely, 2^6561021 is an apocalyptic number.

It is an amenable number.

6561021 is a deficient number, since it is larger than the sum of its proper divisors (2307139).

6561021 is a wasteful number, since it uses less digits than its factorization.

6561021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30035.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 6561021 is about 2561.4490039819. The cubic root of 6561021 is about 187.2077438082.

Adding to 6561021 its reverse (1201656), we get a palindrome (7762677).

The spelling of 6561021 in words is "six million, five hundred sixty-one thousand, twenty-one".