21201021321 has 24 divisors (see below), whose sum is σ = 29077124832. Its totient is φ = 13732545600.

The previous prime is 21201021299. The next prime is 21201021323. The reversal of 21201021321 is 12312010212.

It is not a de Polignac number, because 21201021321 - 2¹³ = 21201013129 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21201021321.

It is not an unprimeable number, because it can be changed into a prime (21201021323) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9032070 + ... + 9034416.

It is an arithmetic number, because the mean of its divisors is an integer number (1211546868).

Almost surely, 2^21201021321 is an apocalyptic number.

It is an amenable number.

21201021321 is a deficient number, since it is larger than the sum of its proper divisors (7876103511).

21201021321 is an equidigital number, since it uses as much as digits as its factorization.

21201021321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2933 (or 2662 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21201021321 its reverse (12312010212), we get a palindrome (33513031533).

The spelling of 21201021321 in words is "twenty-one billion, two hundred one million, twenty-one thousand, three hundred twenty-one".