91320221 has 4 divisors (see below), whose sum is σ = 91474812. Its totient is φ = 91165632.

The previous prime is 91320211. The next prime is 91320301. The reversal of 91320221 is 12202319.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 64176121 + 27144100 = 8011^2 + 5210^2 .

It is a cyclic number.

It is not a de Polignac number, because 91320221 - 2¹⁴ = 91303837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91320193 and 91320202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91320211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76406 + ... + 77591.

It is an arithmetic number, because the mean of its divisors is an integer number (22868703).

Almost surely, 2^91320221 is an apocalyptic number.

It is an amenable number.

91320221 is a deficient number, since it is larger than the sum of its proper divisors (154591).

91320221 is a wasteful number, since it uses less digits than its factorization.

91320221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154590.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 91320221 is about 9556.1614155476. The cubic root of 91320221 is about 450.3211222314.

The spelling of 91320221 in words is "ninety-one million, three hundred twenty thousand, two hundred twenty-one".