91891280 has 80 divisors (see below), whose sum is σ = 232016400. Its totient is φ = 33644544.

The previous prime is 91891271. The next prime is 91891357. The reversal of 91891280 is 8219819.

It can be written as a sum of positive squares in 8 ways, for example, as 15713296 + 76177984 = 3964^2 + 8728^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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, 154664 + ... + 155256.

It is an arithmetic number, because the mean of its divisors is an integer number (2900205).

Almost surely, 2^91891280 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 91891280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116008200).

91891280 is an abundant number, since it is smaller than the sum of its proper divisors (140125120).

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

91891280 is a wasteful number, since it uses less digits than its factorization.

91891280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768 (or 762 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 91891280 is about 9585.9939495078. The cubic root of 91891280 is about 451.2578470256.

The spelling of 91891280 in words is "ninety-one million, eight hundred ninety-one thousand, two hundred eighty".