21255536655444 has 288 divisors, whose sum is σ = 65462443038720. Its totient is φ = 5310058989312.

The previous prime is 21255536655439. The next prime is 21255536655527. The reversal of 21255536655444 is 44455663555212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 17521747 + ... + 18695525.

It is an arithmetic number, because the mean of its divisors is an integer number (227300149440).

Almost surely, 2^{21255536655444} 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 21255536655444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32731221519360).

21255536655444 is an abundant number, since it is smaller than the sum of its proper divisors (44206906383276).

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

21255536655444 is a wasteful number, since it uses less digits than its factorization.

21255536655444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1173939 (or 1173930 counting only the distinct ones).

The product of its digits is 86400000, while the sum is 57.

The spelling of 21255536655444 in words is "twenty-one trillion, two hundred fifty-five billion, five hundred thirty-six million, six hundred fifty-five thousand, four hundred forty-four".