21223616550 has 96 divisors (see below), whose sum is σ = 55712267520. Its totient is φ = 5332003200.

The previous prime is 21223616543. The next prime is 21223616591. The reversal of 21223616550 is 5561632212.

It is a super-2 number, since 2×21223616550² (a number of 21 digits) contains 22 as substring.

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, 495279 + ... + 536421.

It is an arithmetic number, because the mean of its divisors is an integer number (580336120).

Almost surely, 2^21223616550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21223616550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27856133760).

21223616550 is an abundant number, since it is smaller than the sum of its proper divisors (34488650970).

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

21223616550 is a wasteful number, since it uses less digits than its factorization.

21223616550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41358 (or 41353 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 33.

The spelling of 21223616550 in words is "twenty-one billion, two hundred twenty-three million, six hundred sixteen thousand, five hundred fifty".