21331123424 has 48 divisors (see below), whose sum is σ = 45337022640. Its totient is φ = 9820984320.

The previous prime is 21331123403. The next prime is 21331123441. The reversal of 21331123424 is 42432113312.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a junction number, because it is equal to n+sod(n) for n = 21331123393 and 21331123402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 107459 + ... + 232829.

It is an arithmetic number, because the mean of its divisors is an integer number (944521305).

Almost surely, 2^21331123424 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 21331123424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22668511320).

21331123424 is an abundant number, since it is smaller than the sum of its proper divisors (24005899216).

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

21331123424 is a wasteful number, since it uses less digits than its factorization.

21331123424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125803 (or 125795 counting only the distinct ones).

The product of its digits is 3456, while the sum is 26.

Adding to 21331123424 its reverse (42432113312), we get a palindrome (63763236736).

The spelling of 21331123424 in words is "twenty-one billion, three hundred thirty-one million, one hundred twenty-three thousand, four hundred twenty-four".