6556421 has 2 divisors, whose sum is σ = 6556422. Its totient is φ = 6556420.

The previous prime is 6556399. The next prime is 6556439. The reversal of 6556421 is 1246556.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4264225 + 2292196 = 2065^2 + 1514^2 .

It is a cyclic number.

It is not a de Polignac number, because 6556421 - 2¹⁰ = 6555397 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 (6556621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3278210 + 3278211.

It is an arithmetic number, because the mean of its divisors is an integer number (3278211).

Almost surely, 2^6556421 is an apocalyptic number.

It is an amenable number.

6556421 is a deficient number, since it is larger than the sum of its proper divisors (1).

6556421 is an equidigital number, since it uses as much as digits as its factorization.

6556421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 29.

The square root of 6556421 is about 2560.5509172832. The cubic root of 6556421 is about 187.1639824812.

The spelling of 6556421 in words is "six million, five hundred fifty-six thousand, four hundred twenty-one".