21240423444 has 12 divisors (see below), whose sum is σ = 49560988064. Its totient is φ = 7080141144.

The previous prime is 21240423431. The next prime is 21240423461. The reversal of 21240423444 is 44432404212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-3 number, since 3×21240423444³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 885017632 + ... + 885017655.

Almost surely, 2^21240423444 is an apocalyptic number.

It is an amenable number.

21240423444 is an abundant number, since it is smaller than the sum of its proper divisors (28320564620).

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

21240423444 is a wasteful number, since it uses less digits than its factorization.

21240423444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1770035294 (or 1770035292 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 30.

Adding to 21240423444 its reverse (44432404212), we get a palindrome (65672827656).

The spelling of 21240423444 in words is "twenty-one billion, two hundred forty million, four hundred twenty-three thousand, four hundred forty-four".