21243124131240 has 256 divisors, whose sum is σ = 70386048230400. Its totient is φ = 5086299340800.

The previous prime is 21243124131239. The next prime is 21243124131337. The reversal of 21243124131240 is 4213142134212.

It is a happy number.

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 = 21243124131198 and 21243124131207.

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, 35111695 + ... + 35711585.

It is an arithmetic number, because the mean of its divisors is an integer number (274945500900).

Almost surely, 2^{21243124131240} is an apocalyptic number.

21243124131240 is a gapful number since it is divisible by the number (20) 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 21243124131240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35193024115200).

21243124131240 is an abundant number, since it is smaller than the sum of its proper divisors (49142924099160).

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

21243124131240 is a wasteful number, since it uses less digits than its factorization.

21243124131240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 600248 (or 600244 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

Adding to 21243124131240 its reverse (4213142134212), we get a palindrome (25456266265452).

The spelling of 21243124131240 in words is "twenty-one trillion, two hundred forty-three billion, one hundred twenty-four million, one hundred thirty-one thousand, two hundred forty".