991223101440 has 1920 divisors, whose sum is σ = 4273370861760. Its totient is φ = 216583372800.

The previous prime is 991223101399. The next prime is 991223101441. The reversal of 991223101440 is 44101322199.

991223101440 is a `hidden beast` number, since 9 + 91 + 2 + 23 + 101 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (1920).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 991223101395 and 991223101404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991223101441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 7235205052 + ... + 7235205188.

Almost surely, 2^991223101440 is an apocalyptic number.

991223101440 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 991223101440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2136685430880).

991223101440 is an abundant number, since it is smaller than the sum of its proper divisors (3282147760320).

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

991223101440 is a wasteful number, since it uses less digits than its factorization.

991223101440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261 (or 232 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The spelling of 991223101440 in words is "nine hundred ninety-one billion, two hundred twenty-three million, one hundred one thousand, four hundred forty".