6556621 has 2 divisors, whose sum is σ = 6556622. Its totient is φ = 6556620.

The previous prime is 6556609. The next prime is 6556631. The reversal of 6556621 is 1266556.

6556621 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4351396 + 2205225 = 2086^2 + 1485^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6556621 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6556601) 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, 3278310 + 3278311.

It is an arithmetic number, because the mean of its divisors is an integer number (3278311).

Almost surely, 2^6556621 is an apocalyptic number.

It is an amenable number.

6556621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6556621 is an equidigital number, since it uses as much as digits as its factorization.

6556621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10800, while the sum is 31.

The square root of 6556621 is about 2560.5899710809. The cubic root of 6556621 is about 187.1658855732.

The spelling of 6556621 in words is "six million, five hundred fifty-six thousand, six hundred twenty-one".