21201865552 has 80 divisors (see below), whose sum is σ = 48534393600. Its totient is φ = 8783354880.

The previous prime is 21201865549. The next prime is 21201865567. The reversal of 21201865552 is 25556810212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 479349 + ... + 521707.

It is an arithmetic number, because the mean of its divisors is an integer number (606679920).

Almost surely, 2^21201865552 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 21201865552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24267196800).

21201865552 is an abundant number, since it is smaller than the sum of its proper divisors (27332528048).

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

21201865552 is a wasteful number, since it uses less digits than its factorization.

21201865552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42524 (or 42518 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 37.

The spelling of 21201865552 in words is "twenty-one billion, two hundred one million, eight hundred sixty-five thousand, five hundred fifty-two".