21231220313 has 4 divisors (see below), whose sum is σ = 21246079140. Its totient is φ = 21216361488.

The previous prime is 21231220291. The next prime is 21231220343. The reversal of 21231220313 is 31302213212.

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 3637054864 + 17594165449 = 60308^2 + 132643^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231220313 - 2⁶ = 21231220249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21231220343) 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, 7427270 + ... + 7430127.

It is an arithmetic number, because the mean of its divisors is an integer number (5311519785).

Almost surely, 2^21231220313 is an apocalyptic number.

It is an amenable number.

21231220313 is a deficient number, since it is larger than the sum of its proper divisors (14858827).

21231220313 is a wasteful number, since it uses less digits than its factorization.

21231220313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14858826.

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

Adding to 21231220313 its reverse (31302213212), we get a palindrome (52533433525).

The spelling of 21231220313 in words is "twenty-one billion, two hundred thirty-one million, two hundred twenty thousand, three hundred thirteen".