21213231231 has 4 divisors (see below), whose sum is σ = 28284308312. Its totient is φ = 14142154152.

The previous prime is 21213231209. The next prime is 21213231233. The reversal of 21213231231 is 13213231212.

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

It is not a de Polignac number, because 21213231231 - 2⁷ = 21213231103 is a prime.

It is a super-2 number, since 2×21213231231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21213231198 and 21213231207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213231233) 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, 3535538536 + ... + 3535538541.

It is an arithmetic number, because the mean of its divisors is an integer number (7071077078).

Almost surely, 2^21213231231 is an apocalyptic number.

21213231231 is a deficient number, since it is larger than the sum of its proper divisors (7071077081).

21213231231 is an equidigital number, since it uses as much as digits as its factorization.

21213231231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7071077080.

The product of its digits is 432, while the sum is 21.

Adding to 21213231231 its reverse (13213231212), we get a palindrome (34426462443).

The spelling of 21213231231 in words is "twenty-one billion, two hundred thirteen million, two hundred thirty-one thousand, two hundred thirty-one".