647198221 has 2 divisors, whose sum is σ = 647198222. Its totient is φ = 647198220.

The previous prime is 647198179. The next prime is 647198267. The reversal of 647198221 is 122891746.

647198221 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., 644906025 + 2292196 = 25395^2 + 1514^2 .

It is a cyclic number.

It is not a de Polignac number, because 647198221 - 2⁷ = 647198093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647198281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323599110 + 323599111.

It is an arithmetic number, because the mean of its divisors is an integer number (323599111).

Almost surely, 2^647198221 is an apocalyptic number.

It is an amenable number.

647198221 is a deficient number, since it is larger than the sum of its proper divisors (1).

647198221 is an equidigital number, since it uses as much as digits as its factorization.

647198221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 40.

The square root of 647198221 is about 25440.0908213788. The cubic root of 647198221 is about 864.9926919761.

The spelling of 647198221 in words is "six hundred forty-seven million, one hundred ninety-eight thousand, two hundred twenty-one".