6681421 has 2 divisors, whose sum is σ = 6681422. Its totient is φ = 6681420.

The previous prime is 6681419. The next prime is 6681427. The reversal of 6681421 is 1241866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4473225 + 2208196 = 2115^2 + 1486^2 .

It is a cyclic number.

It is not a de Polignac number, because 6681421 - 2¹ = 6681419 is a prime.

Together with 6681419, 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 6681421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6681427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3340710 + 3340711.

It is an arithmetic number, because the mean of its divisors is an integer number (3340711).

Almost surely, 2^6681421 is an apocalyptic number.

It is an amenable number.

6681421 is a deficient number, since it is larger than the sum of its proper divisors (1).

6681421 is an equidigital number, since it uses as much as digits as its factorization.

6681421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 28.

The square root of 6681421 is about 2584.8444827494. The cubic root of 6681421 is about 188.3459470672.

The spelling of 6681421 in words is "six million, six hundred eighty-one thousand, four hundred twenty-one".