6820421 has 2 divisors, whose sum is σ = 6820422. Its totient is φ = 6820420.

The previous prime is 6820393. The next prime is 6820433. The reversal of 6820421 is 1240286.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6477025 + 343396 = 2545^2 + 586^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6820421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6820441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3410210 + 3410211.

It is an arithmetic number, because the mean of its divisors is an integer number (3410211).

Almost surely, 2^6820421 is an apocalyptic number.

It is an amenable number.

6820421 is a deficient number, since it is larger than the sum of its proper divisors (1).

6820421 is an equidigital number, since it uses as much as digits as its factorization.

6820421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 6820421 is about 2611.5935748121. The cubic root of 6820421 is about 189.6431065826.

The spelling of 6820421 in words is "six million, eight hundred twenty thousand, four hundred twenty-one".