21011021320 has 16 divisors (see below), whose sum is σ = 47274798060. Its totient is φ = 8404408512.

The previous prime is 21011021309. The next prime is 21011021393. The reversal of 21011021320 is 2312011012.

It can be written as a sum of positive squares in 2 ways, for example, as 20202073956 + 808947364 = 142134^2 + 28442^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21011021320.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 262637727 + ... + 262637806.

Almost surely, 2^21011021320 is an apocalyptic number.

21011021320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011021320 is an abundant number, since it is smaller than the sum of its proper divisors (26263776740).

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

21011021320 is a wasteful number, since it uses less digits than its factorization.

21011021320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525275544 (or 525275540 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21011021320 its reverse (2312011012), we get a palindrome (23323032332).

The spelling of 21011021320 in words is "twenty-one billion, eleven million, twenty-one thousand, three hundred twenty".