21321201305 has 4 divisors (see below), whose sum is σ = 25585441572. Its totient is φ = 17056961040.

The previous prime is 21321201299. The next prime is 21321201311. The reversal of 21321201305 is 50310212312.

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

It is an interprime number because it is at equal distance from previous prime (21321201299) and next prime (21321201311).

It can be written as a sum of positive squares in 2 ways, for example, as 12768096016 + 8553105289 = 112996^2 + 92483^2 .

It is not a de Polignac number, because 21321201305 - 2⁴ = 21321201289 is a prime.

It is a Duffinian number.

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, 2132120126 + ... + 2132120135.

It is an arithmetic number, because the mean of its divisors is an integer number (6396360393).

Almost surely, 2^21321201305 is an apocalyptic number.

It is an amenable number.

21321201305 is a deficient number, since it is larger than the sum of its proper divisors (4264240267).

21321201305 is an equidigital number, since it uses as much as digits as its factorization.

21321201305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4264240266.

The product of its (nonzero) digits is 360, while the sum is 20.

Adding to 21321201305 its reverse (50310212312), we get a palindrome (71631413617).

The spelling of 21321201305 in words is "twenty-one billion, three hundred twenty-one million, two hundred one thousand, three hundred five".