678221 has 2 divisors, whose sum is σ = 678222. Its totient is φ = 678220.

The previous prime is 678217. The next prime is 678229. The reversal of 678221 is 122876.

678221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 662596 + 15625 = 814^2 + 125^2 .

It is a cyclic number.

It is not a de Polignac number, because 678221 - 2² = 678217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (678229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339110 + 339111.

It is an arithmetic number, because the mean of its divisors is an integer number (339111).

2⁶⁷⁸²²¹ is an apocalyptic number.

It is an amenable number.

678221 is a deficient number, since it is larger than the sum of its proper divisors (1).

678221 is an equidigital number, since it uses as much as digits as its factorization.

678221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1344, while the sum is 26.

The square root of 678221 is about 823.5417415043. The cubic root of 678221 is about 87.8598405890.

The spelling of 678221 in words is "six hundred seventy-eight thousand, two hundred twenty-one".