21243423444 has 24 divisors (see below), whose sum is σ = 51166956288. Its totient is φ = 6852717120.

The previous prime is 21243423391. The next prime is 21243423449. The reversal of 21243423444 is 44432434212.

It is a super-2 number, since 2×21243423444² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243423449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28552617 + ... + 28553360.

It is an arithmetic number, because the mean of its divisors is an integer number (2131956512).

Almost surely, 2^21243423444 is an apocalyptic number.

It is an amenable number.

21243423444 is an abundant number, since it is smaller than the sum of its proper divisors (29923532844).

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

21243423444 is a wasteful number, since it uses less digits than its factorization.

21243423444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57106015 (or 57106013 counting only the distinct ones).

The product of its digits is 73728, while the sum is 33.

Adding to 21243423444 its reverse (44432434212), we get a palindrome (65675857656).

The spelling of 21243423444 in words is "twenty-one billion, two hundred forty-three million, four hundred twenty-three thousand, four hundred forty-four".