21320213231 has 4 divisors (see below), whose sum is σ = 21473596200. Its totient is φ = 21166830264.

The previous prime is 21320213209. The next prime is 21320213279. The reversal of 21320213231 is 13231202312.

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

It is a cyclic number.

It is not a de Polignac number, because 21320213231 - 2¹⁴ = 21320196847 is a prime.

It is a super-2 number, since 2×21320213231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320213531) 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, 76691276 + ... + 76691553.

It is an arithmetic number, because the mean of its divisors is an integer number (5368399050).

Almost surely, 2^21320213231 is an apocalyptic number.

21320213231 is a deficient number, since it is larger than the sum of its proper divisors (153382969).

21320213231 is a wasteful number, since it uses less digits than its factorization.

21320213231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153382968.

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

Adding to 21320213231 its reverse (13231202312), we get a palindrome (34551415543).

The spelling of 21320213231 in words is "twenty-one billion, three hundred twenty million, two hundred thirteen thousand, two hundred thirty-one".