21243233440 has 96 divisors (see below), whose sum is σ = 58961177856. Its totient is φ = 7130588160.

The previous prime is 21243233387. The next prime is 21243233449. The reversal of 21243233440 is 4433234212.

It is a junction number, because it is equal to n+sod(n) for n = 21243233399 and 21243233408.

It is not an unprimeable number, because it can be changed into a prime (21243233449) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 441352 + ... + 487111.

It is an arithmetic number, because the mean of its divisors is an integer number (614178936).

Almost surely, 2^21243233440 is an apocalyptic number.

21243233440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21243233440 is an abundant number, since it is smaller than the sum of its proper divisors (37717944416).

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

21243233440 is a wasteful number, since it uses less digits than its factorization.

21243233440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 928502 (or 928494 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 28.

Adding to 21243233440 its reverse (4433234212), we get a palindrome (25676467652).

The spelling of 21243233440 in words is "twenty-one billion, two hundred forty-three million, two hundred thirty-three thousand, four hundred forty".