91217920 has 112 divisors (see below), whose sum is σ = 233556048. Its totient is φ = 34078720.

The previous prime is 91217899. The next prime is 91217923. The reversal of 91217920 is 2971219.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91217923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 696255 + ... + 696385.

Almost surely, 2^91217920 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 91217920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116778024).

91217920 is an abundant number, since it is smaller than the sum of its proper divisors (142338128).

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

91217920 is a wasteful number, since it uses less digits than its factorization.

91217920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179 (or 155 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 31.

The square root of 91217920 is about 9550.8072957211. The cubic root of 91217920 is about 450.1529027727.

The spelling of 91217920 in words is "ninety-one million, two hundred seventeen thousand, nine hundred twenty".