12121991424 has 108 divisors (see below), whose sum is σ = 35014136976. Its totient is φ = 4033330176.

The previous prime is 12121991419. The next prime is 12121991443. The reversal of 12121991424 is 42419912121.

12121991424 is a `hidden beast` number, since 1 + 212 + 19 + 9 + 1 + 424 = 666.

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

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 1347967 + ... + 1356929.

It is an arithmetic number, because the mean of its divisors is an integer number (324204972).

Almost surely, 2^12121991424 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 12121991424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17507068488).

12121991424 is an abundant number, since it is smaller than the sum of its proper divisors (22892145552).

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

12121991424 is an equidigital number, since it uses as much as digits as its factorization.

12121991424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9572 (or 9555 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The spelling of 12121991424 in words is "twelve billion, one hundred twenty-one million, nine hundred ninety-one thousand, four hundred twenty-four".