21213320231 has 4 divisors (see below), whose sum is σ = 21432014352. Its totient is φ = 20994626112.

The previous prime is 21213320221. The next prime is 21213320237. The reversal of 21213320231 is 13202331212.

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 21213320231 - 2¹⁰ = 21213319207 is a prime.

It is a super-2 number, since 2×21213320231² (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 (21213320237) 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, 109346915 + ... + 109347108.

It is an arithmetic number, because the mean of its divisors is an integer number (5358003588).

Almost surely, 2^21213320231 is an apocalyptic number.

21213320231 is a deficient number, since it is larger than the sum of its proper divisors (218694121).

21213320231 is an equidigital number, since it uses as much as digits as its factorization.

21213320231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218694120.

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

Adding to 21213320231 its reverse (13202331212), we get a palindrome (34415651443).

The spelling of 21213320231 in words is "twenty-one billion, two hundred thirteen million, three hundred twenty thousand, two hundred thirty-one".