21556401104 has 80 divisors (see below), whose sum is σ = 50428915200. Its totient is φ = 8730043392.

The previous prime is 21556401101. The next prime is 21556401109. The reversal of 21556401104 is 40110465512.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556401101) 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, 82052 + ... + 223260.

It is an arithmetic number, because the mean of its divisors is an integer number (630361440).

Almost surely, 2^21556401104 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 21556401104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25214457600).

21556401104 is an abundant number, since it is smaller than the sum of its proper divisors (28872514096).

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

21556401104 is a wasteful number, since it uses less digits than its factorization.

21556401104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141300 (or 141294 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 29.

Adding to 21556401104 its reverse (40110465512), we get a palindrome (61666866616).

The spelling of 21556401104 in words is "twenty-one billion, five hundred fifty-six million, four hundred one thousand, one hundred four".