21444140400 has 120 divisors (see below), whose sum is σ = 68730720000. Its totient is φ = 5715275520.

The previous prime is 21444140387. The next prime is 21444140407. The reversal of 21444140400 is 404144412.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-3 number, since 3×21444140400³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21444140407) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2855851 + ... + 2863349.

It is an arithmetic number, because the mean of its divisors is an integer number (572756000).

Almost surely, 2^21444140400 is an apocalyptic number.

21444140400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21444140400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34365360000).

21444140400 is an abundant number, since it is smaller than the sum of its proper divisors (47286579600).

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

21444140400 is a wasteful number, since it uses less digits than its factorization.

21444140400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9903 (or 9892 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21444140400 its reverse (404144412), we get a palindrome (21848284812).

The spelling of 21444140400 in words is "twenty-one billion, four hundred forty-four million, one hundred forty thousand, four hundred".