21124131840 has 528 divisors, whose sum is σ = 85652506368. Its totient is φ = 4712988672.

The previous prime is 21124131827. The next prime is 21124131841. The reversal of 21124131840 is 4813142112.

It is not an unprimeable number, because it can be changed into a prime (21124131841) 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 47 ways as a sum of consecutive naturals, for example, 13869319 + ... + 13870841.

It is an arithmetic number, because the mean of its divisors is an integer number (162220656).

Almost surely, 2^21124131840 is an apocalyptic number.

21124131840 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 21124131840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42826253184).

21124131840 is an abundant number, since it is smaller than the sum of its proper divisors (64528374528).

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

21124131840 is a wasteful number, since it uses less digits than its factorization.

21124131840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1604 (or 1583 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

Adding to 21124131840 its reverse (4813142112), we get a palindrome (25937273952).

The spelling of 21124131840 in words is "twenty-one billion, one hundred twenty-four million, one hundred thirty-one thousand, eight hundred forty".