91289640 has 128 divisors (see below), whose sum is σ = 297763200. Its totient is φ = 22256640.

The previous prime is 91289591. The next prime is 91289641. The reversal of 91289640 is 4698219.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (91289641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 216630 + ... + 217050.

It is an arithmetic number, because the mean of its divisors is an integer number (2326275).

Almost surely, 2^91289640 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 91289640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148881600).

91289640 is an abundant number, since it is smaller than the sum of its proper divisors (206473560).

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

91289640 is a wasteful number, since it uses less digits than its factorization.

91289640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587 (or 583 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 91289640 is about 9554.5612144148. The cubic root of 91289640 is about 450.2708492922.

The spelling of 91289640 in words is "ninety-one million, two hundred eighty-nine thousand, six hundred forty".