21212200123 has 4 divisors (see below), whose sum is σ = 21612430368. Its totient is φ = 20811969880.

The previous prime is 21212200043. The next prime is 21212200147. The reversal of 21212200123 is 32100221212.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212200123 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212200097 and 21212200106.

It is not an unprimeable number, because it can be changed into a prime (21212206123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200115043 + ... + 200115148.

It is an arithmetic number, because the mean of its divisors is an integer number (5403107592).

Almost surely, 2^21212200123 is an apocalyptic number.

21212200123 is a deficient number, since it is larger than the sum of its proper divisors (400230245).

21212200123 is an equidigital number, since it uses as much as digits as its factorization.

21212200123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400230244.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21212200123 its reverse (32100221212), we get a palindrome (53312421335).

The spelling of 21212200123 in words is "twenty-one billion, two hundred twelve million, two hundred thousand, one hundred twenty-three".