6978221 has 2 divisors, whose sum is σ = 6978222. Its totient is φ = 6978220.

The previous prime is 6978199. The next prime is 6978227. The reversal of 6978221 is 1228796.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6604900 + 373321 = 2570^2 + 611^2 .

It is a cyclic number.

It is not a de Polignac number, because 6978221 - 2¹⁸ = 6716077 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6978227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3489110 + 3489111.

It is an arithmetic number, because the mean of its divisors is an integer number (3489111).

Almost surely, 2^6978221 is an apocalyptic number.

It is an amenable number.

6978221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6978221 is an equidigital number, since it uses as much as digits as its factorization.

6978221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 6978221 is about 2641.6322605541. The cubic root of 6978221 is about 191.0945229903.

The spelling of 6978221 in words is "six million, nine hundred seventy-eight thousand, two hundred twenty-one".