21232123213 has 6 divisors (see below), whose sum is σ = 24698592366.
Its totient is φ = 18198962712.
The previous prime is 21232123207. The next prime is 21232123217. The reversal of 21232123213 is 31232123212.
It can be written as a sum of positive squares in only one way, i.e., 20983840164 + 248283049 = 144858^2 + 15757^2
It is a de Polignac number, because none of the positive numbers 2k-21232123213 is a prime.
It is a super-2 number, since 2×212321232132 (a number of 21 digits) contains 22 as substring.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (21232123217) by changing a digit.
It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 216654270 + ... + 216654367.
It is an arithmetic number, because the mean of its divisors is an integer number (4116432061).
Almost surely, 221232123213 is an apocalyptic number.
It is an amenable number.
21232123213 is a deficient number, since it is larger than the sum of its proper divisors (3466469153).
21232123213 is an equidigital number, since it uses as much as digits as its factorization.
21232123213 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 433308651 (or 433308644 counting only the distinct ones).
The product of its digits is 864, while the sum is 22.
Adding to 21232123213 its reverse (31232123212), we get a palindrome (52464246425).
Subtracting 21232123213 from its reverse (31232123212), we obtain a palindrome (9999999999).
The spelling of 21232123213 in words is "twenty-one billion, two hundred thirty-two million, one hundred twenty-three thousand, two hundred thirteen".