8709221 has 2 divisors, whose sum is σ = 8709222. Its totient is φ = 8709220.

The previous prime is 8709191. The next prime is 8709229. The reversal of 8709221 is 1229078.

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., 7924225 + 784996 = 2815^2 + 886^2 .

It is a cyclic number.

It is not a de Polignac number, because 8709221 - 2¹⁰ = 8708197 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8709229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4354610 + 4354611.

It is an arithmetic number, because the mean of its divisors is an integer number (4354611).

Almost surely, 2^8709221 is an apocalyptic number.

It is an amenable number.

8709221 is a deficient number, since it is larger than the sum of its proper divisors (1).

8709221 is an equidigital number, since it uses as much as digits as its factorization.

8709221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 8709221 is about 2951.1389326834. The cubic root of 8709221 is about 205.7436485084.

The spelling of 8709221 in words is "eight million, seven hundred nine thousand, two hundred twenty-one".