21255334344 has 72 divisors (see below), whose sum is σ = 58526452530. Its totient is φ = 6968874240.

The previous prime is 21255334339. The next prime is 21255334369. The reversal of 21255334344 is 44343355212.

21255334344 is a `hidden beast` number, since 21 + 2 + 553 + 3 + 43 + 44 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 2434238244 + 18821096100 = 49338^2 + 137190^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21255334299 and 21255334308.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 228244 + ... + 307580.

Almost surely, 2^21255334344 is an apocalyptic number.

21255334344 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21255334344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29263226265).

21255334344 is an abundant number, since it is smaller than the sum of its proper divisors (37271118186).

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

21255334344 is a wasteful number, since it uses less digits than its factorization.

21255334344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79471 (or 79403 counting only the distinct ones).

The product of its digits is 172800, while the sum is 36.

Adding to 21255334344 its reverse (44343355212), we get a palindrome (65598689556).

The spelling of 21255334344 in words is "twenty-one billion, two hundred fifty-five million, three hundred thirty-four thousand, three hundred forty-four".