21636503280 has 480 divisors, whose sum is σ = 86490892800. Its totient is φ = 4742535168.

The previous prime is 21636503269. The next prime is 21636503281. The reversal of 21636503280 is 8230563612.

It is a happy number.

21636503280 is a `hidden beast` number, since 2 + 16 + 365 + 0 + 3 + 280 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636503281) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 26162227 + ... + 26163053.

It is an arithmetic number, because the mean of its divisors is an integer number (180189360).

Almost surely, 2^21636503280 is an apocalyptic number.

21636503280 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 21636503280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43245446400).

21636503280 is an abundant number, since it is smaller than the sum of its proper divisors (64854389520).

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

21636503280 is a wasteful number, since it uses less digits than its factorization.

21636503280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061 (or 1052 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 21636503280 in words is "twenty-one billion, six hundred thirty-six million, five hundred three thousand, two hundred eighty".