21320212321 has 4 divisors (see below), whose sum is σ = 21722480532. Its totient is φ = 20917944112.

The previous prime is 21320212307. The next prime is 21320212327. The reversal of 21320212321 is 12321202312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14733104400 + 6587107921 = 121380^2 + 81161^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21320212321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21320212327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 201134026 + ... + 201134131.

It is an arithmetic number, because the mean of its divisors is an integer number (5430620133).

Almost surely, 2^21320212321 is an apocalyptic number.

It is an amenable number.

21320212321 is a deficient number, since it is larger than the sum of its proper divisors (402268211).

21320212321 is an equidigital number, since it uses as much as digits as its factorization.

21320212321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402268210.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21320212321 its reverse (12321202312), we get a palindrome (33641414633).

The spelling of 21320212321 in words is "twenty-one billion, three hundred twenty million, two hundred twelve thousand, three hundred twenty-one".