21021321321 has 192 divisors, whose sum is σ = 44664721920. Its totient is φ = 9158123520.

The previous prime is 21021321311. The next prime is 21021321337. The reversal of 21021321321 is 12312312012.

21021321321 is a `hidden beast` number, since 2 + 1 + 0 + 21 + 321 + 321 = 666.

It is not a de Polignac number, because 21021321321 - 2⁹ = 21021320809 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021321294 and 21021321303.

It is not an unprimeable number, because it can be changed into a prime (21021321311) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 4439071 + ... + 4443803.

It is an arithmetic number, because the mean of its divisors is an integer number (232628760).

Almost surely, 2^21021321321 is an apocalyptic number.

21021321321 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21021321321 is an abundant number, since it is smaller than the sum of its proper divisors (23643400599).

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

21021321321 is a wasteful number, since it uses less digits than its factorization.

21021321321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4816 (or 4813 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21021321321 its reverse (12312312012), we get a palindrome (33333633333).

The spelling of 21021321321 in words is "twenty-one billion, twenty-one million, three hundred twenty-one thousand, three hundred twenty-one".