21571553344 has 56 divisors (see below), whose sum is σ = 46765195776. Its totient is φ = 9791040000.

The previous prime is 21571553303. The next prime is 21571553369. The reversal of 21571553344 is 44335517512.

It is a junction number, because it is equal to n+sod(n) for n = 21571553297 and 21571553306.

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, 471649 + ... + 515359.

Almost surely, 2^21571553344 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 21571553344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23382597888).

21571553344 is an abundant number, since it is smaller than the sum of its proper divisors (25193642432).

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

21571553344 is a wasteful number, since it uses less digits than its factorization.

21571553344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44435 (or 44425 counting only the distinct ones).

The product of its digits is 252000, while the sum is 40.

The spelling of 21571553344 in words is "twenty-one billion, five hundred seventy-one million, five hundred fifty-three thousand, three hundred forty-four".