91781664 has 96 divisors (see below), whose sum is σ = 261382464. Its totient is φ = 28032000.

The previous prime is 91781663. The next prime is 91781687. The reversal of 91781664 is 46618719.

It is a tau number, because it is divible by the number of its divisors (96).

It is not an unprimeable number, because it can be changed into a prime (91781663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 313102 + ... + 313394.

It is an arithmetic number, because the mean of its divisors is an integer number (2722734).

Almost surely, 2^91781664 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 91781664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130691232).

91781664 is an abundant number, since it is smaller than the sum of its proper divisors (169600800).

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

91781664 is a wasteful number, since it uses less digits than its factorization.

91781664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 570 (or 562 counting only the distinct ones).

The product of its digits is 72576, while the sum is 42.

The square root of 91781664 is about 9580.2747351002. The cubic root of 91781664 is about 451.0783422819.

The spelling of 91781664 in words is "ninety-one million, seven hundred eighty-one thousand, six hundred sixty-four".