91041221 has 2 divisors, whose sum is σ = 91041222. Its totient is φ = 91041220.

The previous prime is 91041211. The next prime is 91041229. The reversal of 91041221 is 12214019.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79744900 + 11296321 = 8930^2 + 3361^2 .

It is an emirp because it is prime and its reverse (12214019) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91041221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 91041193 and 91041202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91041229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45520610 + 45520611.

It is an arithmetic number, because the mean of its divisors is an integer number (45520611).

Almost surely, 2^91041221 is an apocalyptic number.

It is an amenable number.

91041221 is a deficient number, since it is larger than the sum of its proper divisors (1).

91041221 is an equidigital number, since it uses as much as digits as its factorization.

91041221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 91041221 is about 9541.5523370152. The cubic root of 91041221 is about 449.8620498960.

The spelling of 91041221 in words is "ninety-one million, forty-one thousand, two hundred twenty-one".