291009221 has 2 divisors, whose sum is σ = 291009222. Its totient is φ = 291009220.

The previous prime is 291009211. The next prime is 291009241. The reversal of 291009221 is 122900192.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159012100 + 131997121 = 12610^2 + 11489^2 .

It is a cyclic number.

It is not a de Polignac number, because 291009221 - 2¹⁸ = 290747077 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (291009211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145504610 + 145504611.

It is an arithmetic number, because the mean of its divisors is an integer number (145504611).

Almost surely, 2^291009221 is an apocalyptic number.

It is an amenable number.

291009221 is a deficient number, since it is larger than the sum of its proper divisors (1).

291009221 is an equidigital number, since it uses as much as digits as its factorization.

291009221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 291009221 is about 17058.9923793875. The cubic root of 291009221 is about 662.6775380839.

The spelling of 291009221 in words is "two hundred ninety-one million, nine thousand, two hundred twenty-one".