21521401044 has 96 divisors (see below), whose sum is σ = 59214704640. Its totient is φ = 5997628800.

The previous prime is 21521401043. The next prime is 21521401129. The reversal of 21521401044 is 44010412512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521401043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 441897 + ... + 488175.

It is an arithmetic number, because the mean of its divisors is an integer number (616819840).

Almost surely, 2^21521401044 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 21521401044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29607352320).

21521401044 is an abundant number, since it is smaller than the sum of its proper divisors (37693303596).

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

21521401044 is a wasteful number, since it uses less digits than its factorization.

21521401044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46581 (or 46579 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

Adding to 21521401044 its reverse (44010412512), we get a palindrome (65531813556).

The spelling of 21521401044 in words is "twenty-one billion, five hundred twenty-one million, four hundred one thousand, forty-four".