21042051552 has 144 divisors (see below), whose sum is σ = 61731109440. Its totient is φ = 6793860096.

The previous prime is 21042051551. The next prime is 21042051577. The reversal of 21042051552 is 25515024012.

21042051552 is a `hidden beast` number, since 2 + 104 + 2 + 0 + 5 + 1 + 552 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042051551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2435913 + ... + 2444535.

It is an arithmetic number, because the mean of its divisors is an integer number (428688260).

Almost surely, 2^21042051552 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 21042051552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30865554720).

21042051552 is an abundant number, since it is smaller than the sum of its proper divisors (40689057888).

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

21042051552 is a wasteful number, since it uses less digits than its factorization.

21042051552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8905 (or 8894 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 27.

Adding to 21042051552 its reverse (25515024012), we get a palindrome (46557075564).

The spelling of 21042051552 in words is "twenty-one billion, forty-two million, fifty-one thousand, five hundred fifty-two".