21320431013 has 10 divisors (see below), whose sum is σ = 24872359014. Its totient is φ = 18274653096.

The previous prime is 21320431007. The next prime is 21320431019. The reversal of 21320431013 is 31013402312.

It is an interprime number because it is at equal distance from previous prime (21320431007) and next prime (21320431019).

It can be written as a sum of positive squares in only one way, i.e., 20150654209 + 1169776804 = 141953^2 + 34202^2 .

It is not a de Polignac number, because 21320431013 - 2¹⁶ = 21320365477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320431019) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4437506 + ... + 4442307.

Almost surely, 2^21320431013 is an apocalyptic number.

It is an amenable number.

21320431013 is a deficient number, since it is larger than the sum of its proper divisors (3551928001).

21320431013 is an frugal number, since it uses more digits than its factorization.

21320431013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8879841 (or 8879820 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21320431013 its reverse (31013402312), we get a palindrome (52333833325).

The spelling of 21320431013 in words is "twenty-one billion, three hundred twenty million, four hundred thirty-one thousand, thirteen".