21606503520 has 192 divisors, whose sum is σ = 77851017216. Its totient is φ = 4934338560.

The previous prime is 21606503491. The next prime is 21606503539. The reversal of 21606503520 is 2530560612.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5444577 + ... + 5448543.

It is an arithmetic number, because the mean of its divisors is an integer number (405474048).

Almost surely, 2^21606503520 is an apocalyptic number.

21606503520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21606503520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38925508608).

21606503520 is an abundant number, since it is smaller than the sum of its proper divisors (56244513696).

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

21606503520 is a wasteful number, since it uses less digits than its factorization.

21606503520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5613 (or 5605 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 30.

The spelling of 21606503520 in words is "twenty-one billion, six hundred six million, five hundred three thousand, five hundred twenty".