21144244420 has 48 divisors (see below), whose sum is σ = 48355861680. Its totient is φ = 7719376896.

The previous prime is 21144244409. The next prime is 21144244421. The reversal of 21144244420 is 2444244112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 1384881796 + 19759362624 = 37214^2 + 140568^2 .

It is a super-2 number, since 2×21144244420² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21144244421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 433737 + ... + 480016.

It is an arithmetic number, because the mean of its divisors is an integer number (1007413785).

Almost surely, 2^21144244420 is an apocalyptic number.

21144244420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21144244420 is an abundant number, since it is smaller than the sum of its proper divisors (27211617260).

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

21144244420 is a wasteful number, since it uses less digits than its factorization.

21144244420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913864 (or 913862 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 28.

Adding to 21144244420 its reverse (2444244112), we get a palindrome (23588488532).

The spelling of 21144244420 in words is "twenty-one billion, one hundred forty-four million, two hundred forty-four thousand, four hundred twenty".