21042451055550 has 96 divisors (see below), whose sum is σ = 53569701319680. Its totient is φ = 5463029113600.

The previous prime is 21042451055513. The next prime is 21042451055623. The reversal of 21042451055550 is 5555015424012.

It is a happy number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21042451055499 and 21042451055508.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 625692 + ... + 6517391.

It is an arithmetic number, because the mean of its divisors is an integer number (558017722080).

Almost surely, 2^{21042451055550} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21042451055550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26784850659840).

21042451055550 is an abundant number, since it is smaller than the sum of its proper divisors (32527250264130).

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

21042451055550 is a wasteful number, since it uses less digits than its factorization.

21042451055550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7143618 (or 7143613 counting only the distinct ones).

The product of its (nonzero) digits is 200000, while the sum is 39.

Adding to 21042451055550 its reverse (5555015424012), we get a palindrome (26597466479562).

The spelling of 21042451055550 in words is "twenty-one trillion, forty-two billion, four hundred fifty-one million, fifty-five thousand, five hundred fifty".