21144431400 has 96 divisors (see below), whose sum is σ = 65652792000. Its totient is φ = 5629478400.

The previous prime is 21144431389. The next prime is 21144431417. The reversal of 21144431400 is 413444112.

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

It is an unprimeable number.

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, 350676 + ... + 406524.

It is an arithmetic number, because the mean of its divisors is an integer number (683883250).

Almost surely, 2^21144431400 is an apocalyptic number.

21144431400 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 21144431400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32826396000).

21144431400 is an abundant number, since it is smaller than the sum of its proper divisors (44508360600).

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

21144431400 is a wasteful number, since it uses less digits than its factorization.

21144431400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56499 (or 56490 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

Adding to 21144431400 its reverse (413444112), we get a palindrome (21557875512).

The spelling of 21144431400 in words is "twenty-one billion, one hundred forty-four million, four hundred thirty-one thousand, four hundred".