91212140640 has 96 divisors (see below), whose sum is σ = 287967488256. Its totient is φ = 24268275200.

The previous prime is 91212140623. The next prime is 91212140651. The reversal of 91212140640 is 4604121219.

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

It is a super-2 number, since 2×91212140640² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 91212140598 and 91212140607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1836 + ... + 427115.

It is an arithmetic number, because the mean of its divisors is an integer number (2999661336).

Almost surely, 2^91212140640 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 91212140640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143983744128).

91212140640 is an abundant number, since it is smaller than the sum of its proper divisors (196755347616).

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

91212140640 is a wasteful number, since it uses less digits than its factorization.

91212140640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 429412 (or 429404 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

Adding to 91212140640 its reverse (4604121219), we get a palindrome (95816261859).

The spelling of 91212140640 in words is "ninety-one billion, two hundred twelve million, one hundred forty thousand, six hundred forty".