91221 has 8 divisors (see below), whose sum is σ = 131040.
Its totient is φ = 56112.
The previous prime is 91199. The next prime is 91229. The reversal of 91221 is 12219.
It is a happy number.
It is a sphenic number, since it is the product of 3 distinct primes.
It is not a de Polignac number, because 91221 - 29 = 90709 is a prime.
It is a Curzon number.
It is a self number, because there is not a number n which added to its sum of digits gives 91221.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (91229) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1131 + ... + 1208.
It is an arithmetic number, because the mean of its divisors is an integer number (16380).
291221 is an apocalyptic number.
It is an amenable number.
91221 is a deficient number, since it is larger than the sum of its proper divisors (39819).
91221 is a wasteful number, since it uses less digits than its factorization.
91221 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 2355.
The product of its digits is 36, while the sum is 15.
The square root of 91221 is about 302.0281443839.
The cubic root of 91221 is about 45.0157969231.
The spelling of 91221 in words is "ninety-one thousand, two hundred twenty-one".