91811681280 has 704 divisors, whose sum is σ = 359027424000. Its totient is φ = 22065315840.

The previous prime is 91811681243. The next prime is 91811681347. The reversal of 91811681280 is 8218611819.

It is a tau number, because it is divible by the number of its divisors (704).

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, 263070546 + ... + 263070894.

Almost surely, 2^91811681280 is an apocalyptic number.

91811681280 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 91811681280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179513712000).

91811681280 is an abundant number, since it is smaller than the sum of its proper divisors (267215742720).

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

91811681280 is a wasteful number, since it uses less digits than its factorization.

91811681280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567 (or 543 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 45.

The spelling of 91811681280 in words is "ninety-one billion, eight hundred eleven million, six hundred eighty-one thousand, two hundred eighty".