221091 has 8 divisors (see below), whose sum is σ = 317520. Its totient is φ = 136032.

The previous prime is 221087. The next prime is 221093. The reversal of 221091 is 190122.

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 221091 - 2² = 221087 is a prime.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 221091.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221093) 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, 2796 + ... + 2873.

It is an arithmetic number, because the mean of its divisors is an integer number (39690).

2²²¹⁰⁹¹ is an apocalyptic number.

221091 is a deficient number, since it is larger than the sum of its proper divisors (96429).

221091 is a wasteful number, since it uses less digits than its factorization.

221091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5685.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 221091 is about 470.2031475862. The cubic root of 221091 is about 60.4677331754.

The spelling of 221091 in words is "two hundred twenty-one thousand, ninety-one".