21404404044 has 72 divisors (see below), whose sum is σ = 55793687040. Its totient is φ = 6915144672.

The previous prime is 21404404037. The next prime is 21404404051. The reversal of 21404404044 is 44040440412.

21404404044 is a `hidden beast` number, since 2 + 140 + 440 + 40 + 44 = 666.

It is an interprime number because it is at equal distance from previous prime (21404404037) and next prime (21404404051).

It is a junction number, because it is equal to n+sod(n) for n = 21404403999 and 21404404017.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 112867 + ... + 235685.

It is an arithmetic number, because the mean of its divisors is an integer number (774912320).

Almost surely, 2^21404404044 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 21404404044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27896843520).

21404404044 is an abundant number, since it is smaller than the sum of its proper divisors (34389282996).

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

21404404044 is a wasteful number, since it uses less digits than its factorization.

21404404044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122979 (or 122974 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 27.

Adding to 21404404044 its reverse (44040440412), we get a palindrome (65444844456).

The spelling of 21404404044 in words is "twenty-one billion, four hundred four million, four hundred four thousand, forty-four".