21240000444 has 72 divisors (see below), whose sum is σ = 54466890240. Its totient is φ = 6437800512.

The previous prime is 21240000443. The next prime is 21240000493. The reversal of 21240000444 is 44400004212.

It is a super-2 number, since 2×21240000444² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21240000444.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240000443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 57717 + ... + 214035.

Almost surely, 2^21240000444 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 21240000444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27233445120).

21240000444 is an abundant number, since it is smaller than the sum of its proper divisors (33226889796).

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

21240000444 is a wasteful number, since it uses less digits than its factorization.

21240000444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156419 (or 156404 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 21.

Adding to 21240000444 its reverse (44400004212), we get a palindrome (65640004656).

The spelling of 21240000444 in words is "twenty-one billion, two hundred forty million, four hundred forty-four", and thus it is an aban number.