91121220 has 48 divisors (see below), whose sum is σ = 283489920. Its totient is φ = 24298848.

The previous prime is 91121213. The next prime is 91121227. The reversal of 91121220 is 2212119.

It is an interprime number because it is at equal distance from previous prime (91121213) and next prime (91121227).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 91121193 and 91121202.

It is not an unprimeable number, because it can be changed into a prime (91121227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 83832 + ... + 84911.

It is an arithmetic number, because the mean of its divisors is an integer number (5906040).

Almost surely, 2^91121220 is an apocalyptic number.

91121220 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

91121220 is an abundant number, since it is smaller than the sum of its proper divisors (192368700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91121220 is a wasteful number, since it uses less digits than its factorization.

91121220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168761 (or 168753 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 91121220 is about 9545.7435540664. The cubic root of 91121220 is about 449.9937776917.

Adding to 91121220 its reverse (2212119), we get a palindrome (93333339).

The spelling of 91121220 in words is "ninety-one million, one hundred twenty-one thousand, two hundred twenty".