91784281680 has 800 divisors, whose sum is σ = 405082073088. Its totient is φ = 18737049600.

The previous prime is 91784281651. The next prime is 91784281691. The reversal of 91784281680 is 8618248719.

91784281680 is a `hidden beast` number, since 91 + 78 + 428 + 1 + 68 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 18277570 + ... + 18282590.

Almost surely, 2^91784281680 is an apocalyptic number.

91784281680 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91784281680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (202541036544).

91784281680 is an abundant number, since it is smaller than the sum of its proper divisors (313297791408).

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

91784281680 is a wasteful number, since it uses less digits than its factorization.

91784281680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5097 (or 5082 counting only the distinct ones).

The product of its (nonzero) digits is 1548288, while the sum is 54.

The spelling of 91784281680 in words is "ninety-one billion, seven hundred eighty-four million, two hundred eighty-one thousand, six hundred eighty".