21521043444 has 24 divisors (see below), whose sum is σ = 53169637248. Its totient is φ = 6751699840.

The previous prime is 21521043433. The next prime is 21521043487. The reversal of 21521043444 is 44434012512.

It is a super-2 number, since 2×21521043444² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52747452 + ... + 52747859.

It is an arithmetic number, because the mean of its divisors is an integer number (2215401552).

Almost surely, 2^21521043444 is an apocalyptic number.

It is an amenable number.

21521043444 is an abundant number, since it is smaller than the sum of its proper divisors (31648593804).

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

21521043444 is a wasteful number, since it uses less digits than its factorization.

21521043444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105495335 (or 105495333 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 30.

Adding to 21521043444 its reverse (44434012512), we get a palindrome (65955055956).

The spelling of 21521043444 in words is "twenty-one billion, five hundred twenty-one million, forty-three thousand, four hundred forty-four".