6621421 has 2 divisors, whose sum is σ = 6621422. Its totient is φ = 6621420.

The previous prime is 6621413. The next prime is 6621451. The reversal of 6621421 is 1241266.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5593225 + 1028196 = 2365^2 + 1014^2 .

It is a cyclic number.

It is not a de Polignac number, because 6621421 - 2³ = 6621413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6621392 and 6621401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6621451) 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, 3310710 + 3310711.

It is an arithmetic number, because the mean of its divisors is an integer number (3310711).

Almost surely, 2^6621421 is an apocalyptic number.

It is an amenable number.

6621421 is a deficient number, since it is larger than the sum of its proper divisors (1).

6621421 is an equidigital number, since it uses as much as digits as its factorization.

6621421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 22.

The square root of 6621421 is about 2573.2121949035. The cubic root of 6621421 is about 187.7804608725.

Adding to 6621421 its reverse (1241266), we get a palindrome (7862687).

The spelling of 6621421 in words is "six million, six hundred twenty-one thousand, four hundred twenty-one".