220778221 has 2 divisors, whose sum is σ = 220778222. Its totient is φ = 220778220.

The previous prime is 220778209. The next prime is 220778273. The reversal of 220778221 is 122877022.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 213568996 + 7209225 = 14614^2 + 2685^2 .

It is a cyclic number.

It is not a de Polignac number, because 220778221 - 2¹³ = 220770029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (220778321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110389110 + 110389111.

It is an arithmetic number, because the mean of its divisors is an integer number (110389111).

Almost surely, 2^220778221 is an apocalyptic number.

It is an amenable number.

220778221 is a deficient number, since it is larger than the sum of its proper divisors (1).

220778221 is an equidigital number, since it uses as much as digits as its factorization.

220778221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 220778221 is about 14858.6076400180. The cubic root of 220778221 is about 604.3920500832.

The spelling of 220778221 in words is "two hundred twenty million, seven hundred seventy-eight thousand, two hundred twenty-one".