91221648 has 80 divisors (see below), whose sum is σ = 272649216. Its totient is φ = 25741440.

The previous prime is 91221631. The next prime is 91221653. The reversal of 91221648 is 84612219.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26253 + ... + 29523.

Almost surely, 2^91221648 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 91221648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136324608).

91221648 is an abundant number, since it is smaller than the sum of its proper divisors (181427568).

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

91221648 is a wasteful number, since it uses less digits than its factorization.

91221648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3372 (or 3366 counting only the distinct ones).

The product of its digits is 6912, while the sum is 33.

The square root of 91221648 is about 9551.0024604750. The cubic root of 91221648 is about 450.1590351466.

The spelling of 91221648 in words is "ninety-one million, two hundred twenty-one thousand, six hundred forty-eight".