1091221 has 2 divisors, whose sum is σ = 1091222. Its totient is φ = 1091220.

The previous prime is 1091219. The next prime is 1091239. The reversal of 1091221 is 1221901.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 972196 + 119025 = 986^2 + 345^2 .

It is a cyclic number.

It is not a de Polignac number, because 1091221 - 2¹ = 1091219 is a prime.

Together with 1091219, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1091195 and 1091204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1091261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 545610 + 545611.

It is an arithmetic number, because the mean of its divisors is an integer number (545611).

2^1091221 is an apocalyptic number.

It is an amenable number.

1091221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1091221 is an equidigital number, since it uses as much as digits as its factorization.

1091221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 1091221 is about 1044.6152401722. The cubic root of 1091221 is about 102.9526599306.

The spelling of 1091221 in words is "one million, ninety-one thousand, two hundred twenty-one".