21021312320 has 56 divisors (see below), whose sum is σ = 50573126184. Its totient is φ = 8321826816.

The previous prime is 21021312287. The next prime is 21021312343. The reversal of 21021312320 is 2321312012.

It can be written as a sum of positive squares in 4 ways, for example, as 1535385856 + 19485926464 = 39184^2 + 139592^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 307577 + ... + 369656.

It is an arithmetic number, because the mean of its divisors is an integer number (903091539).

Almost surely, 2^21021312320 is an apocalyptic number.

21021312320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021312320 is an abundant number, since it is smaller than the sum of its proper divisors (29551813864).

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

21021312320 is an equidigital number, since it uses as much as digits as its factorization.

21021312320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677347 (or 677337 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21021312320 its reverse (2321312012), we get a palindrome (23342624332).

The spelling of 21021312320 in words is "twenty-one billion, twenty-one million, three hundred twelve thousand, three hundred twenty".