91725421680 has 320 divisors, whose sum is σ = 336953433600. Its totient is φ = 22854389760.

The previous prime is 91725421661. The next prime is 91725421691. The reversal of 91725421680 is 8612452719.

91725421680 is a `hidden beast` number, since 9 + 17 + 2 + 542 + 16 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5095095 + ... + 5113065.

It is an arithmetic number, because the mean of its divisors is an integer number (1052979480).

Almost surely, 2^91725421680 is an apocalyptic number.

91725421680 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 91725421680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168476716800).

91725421680 is an abundant number, since it is smaller than the sum of its proper divisors (245228011920).

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

91725421680 is a wasteful number, since it uses less digits than its factorization.

91725421680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18149 (or 18137 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 91725421680 in words is "ninety-one billion, seven hundred twenty-five million, four hundred twenty-one thousand, six hundred eighty".