21331681280 has 448 divisors, whose sum is σ = 64735130880. Its totient is φ = 6568280064.

The previous prime is 21331681271. The next prime is 21331681297. The reversal of 21331681280 is 8218613312.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (448).

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 21331681280.

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, 219914192 + ... + 219914288.

It is an arithmetic number, because the mean of its divisors is an integer number (144498060).

Almost surely, 2^21331681280 is an apocalyptic number.

21331681280 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 21331681280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32367565440).

21331681280 is an abundant number, since it is smaller than the sum of its proper divisors (43403449600).

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

21331681280 is an equidigital number, since it uses as much as digits as its factorization.

21331681280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207 (or 183 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 35.

The spelling of 21331681280 in words is "twenty-one billion, three hundred thirty-one million, six hundred eighty-one thousand, two hundred eighty".