21209108480 has 208 divisors, whose sum is σ = 58471944960. Its totient is φ = 7233601536.

The previous prime is 21209108477. The next prime is 21209108537. The reversal of 21209108480 is 8480190212.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 21209108480.

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, 48312101 + ... + 48312539.

It is an arithmetic number, because the mean of its divisors is an integer number (281115120).

Almost surely, 2^21209108480 is an apocalyptic number.

21209108480 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 21209108480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29235972480).

21209108480 is an abundant number, since it is smaller than the sum of its proper divisors (37262836480).

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

21209108480 is an equidigital number, since it uses as much as digits as its factorization.

21209108480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812 (or 790 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 35.

Adding to 21209108480 its reverse (8480190212), we get a palindrome (29689298692).

The spelling of 21209108480 in words is "twenty-one billion, two hundred nine million, one hundred eight thousand, four hundred eighty".