91531212864 has 896 divisors, whose sum is σ = 340010496000. Its totient is φ = 21459271680.

The previous prime is 91531212821. The next prime is 91531212869. The reversal of 91531212864 is 46821213519.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (91531212869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 276529179 + ... + 276529509.

It is an arithmetic number, because the mean of its divisors is an integer number (379476000).

Almost surely, 2^91531212864 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 91531212864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (170005248000).

91531212864 is an abundant number, since it is smaller than the sum of its proper divisors (248479283136).

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

91531212864 is a wasteful number, since it uses less digits than its factorization.

91531212864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416 (or 392 counting only the distinct ones).

The product of its digits is 103680, while the sum is 42.

The spelling of 91531212864 in words is "ninety-one billion, five hundred thirty-one million, two hundred twelve thousand, eight hundred sixty-four".