91021200 has 120 divisors (see below), whose sum is σ = 294850176. Its totient is φ = 24000000.

The previous prime is 91021181. The next prime is 91021201. The reversal of 91021200 is 212019.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 91021200.

It is not an unprimeable number, because it can be changed into a prime (91021201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 120825 + ... + 121575.

Almost surely, 2^91021200 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91021200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147425088).

91021200 is an abundant number, since it is smaller than the sum of its proper divisors (203828976).

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

91021200 is a wasteful number, since it uses less digits than its factorization.

91021200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873 (or 862 counting only the distinct ones).

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

The square root of 91021200 is about 9540.5031313867. The cubic root of 91021200 is about 449.8290708846.

Adding to 91021200 its reverse (212019), we get a palindrome (91233219).

The spelling of 91021200 in words is "ninety-one million, twenty-one thousand, two hundred".