21513443444 has 24 divisors (see below), whose sum is σ = 37870224000. Its totient is φ = 10693473120.

The previous prime is 21513443423. The next prime is 21513443489. The reversal of 21513443444 is 44434431512.

It is a happy number.

It is a super-2 number, since 2×21513443444² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 967289 + ... + 989279.

It is an arithmetic number, because the mean of its divisors is an integer number (1577926000).

Almost surely, 2^21513443444 is an apocalyptic number.

It is an amenable number.

21513443444 is a deficient number, since it is larger than the sum of its proper divisors (16356780556).

21513443444 is a wasteful number, since it uses less digits than its factorization.

21513443444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23423 (or 23421 counting only the distinct ones).

The product of its digits is 92160, while the sum is 35.

Adding to 21513443444 its reverse (44434431512), we get a palindrome (65947874956).

The spelling of 21513443444 in words is "twenty-one billion, five hundred thirteen million, four hundred forty-three thousand, four hundred forty-four".