21320320013 has 4 divisors (see below), whose sum is σ = 21328251420. Its totient is φ = 21312388608.

The previous prime is 21320320009. The next prime is 21320320019. The reversal of 21320320013 is 31002302312.

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 3662428324 + 17657891689 = 60518^2 + 132883^2 .

It is a cyclic number.

It is not a de Polignac number, because 21320320013 - 2² = 21320320009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21320319973 and 21320320000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320320019) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3961670 + ... + 3967047.

It is an arithmetic number, because the mean of its divisors is an integer number (5332062855).

Almost surely, 2^21320320013 is an apocalyptic number.

It is an amenable number.

21320320013 is a deficient number, since it is larger than the sum of its proper divisors (7931407).

21320320013 is an equidigital number, since it uses as much as digits as its factorization.

21320320013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7931406.

The product of its (nonzero) digits is 216, while the sum is 17.

Adding to 21320320013 its reverse (31002302312), we get a palindrome (52322622325).

The spelling of 21320320013 in words is "twenty-one billion, three hundred twenty million, three hundred twenty thousand, thirteen".