6840221 has 2 divisors, whose sum is σ = 6840222. Its totient is φ = 6840220.

The previous prime is 6840203. The next prime is 6840241. The reversal of 6840221 is 1220486.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6832996 + 7225 = 2614^2 + 85^2 .

It is a cyclic number.

It is not a de Polignac number, because 6840221 - 2⁶ = 6840157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6840241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3420110 + 3420111.

It is an arithmetic number, because the mean of its divisors is an integer number (3420111).

Almost surely, 2^6840221 is an apocalyptic number.

It is an amenable number.

6840221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6840221 is an equidigital number, since it uses as much as digits as its factorization.

6840221 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 6840221 is about 2615.3816165141. The cubic root of 6840221 is about 189.8264435436.

The spelling of 6840221 in words is "six million, eight hundred forty thousand, two hundred twenty-one".