21204302123 has 4 divisors (see below), whose sum is σ = 21331274160. Its totient is φ = 21077330088.

The previous prime is 21204302111. The next prime is 21204302173. The reversal of 21204302123 is 32120340212.

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 21204302123 - 2²⁴ = 21187524907 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21204302095 and 21204302104.

It is not an unprimeable number, because it can be changed into a prime (21204302173) 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, 63485768 + ... + 63486101.

It is an arithmetic number, because the mean of its divisors is an integer number (5332818540).

Almost surely, 2^21204302123 is an apocalyptic number.

21204302123 is a deficient number, since it is larger than the sum of its proper divisors (126972037).

21204302123 is a wasteful number, since it uses less digits than its factorization.

21204302123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126972036.

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21204302123 its reverse (32120340212), we get a palindrome (53324642335).

The spelling of 21204302123 in words is "twenty-one billion, two hundred four million, three hundred two thousand, one hundred twenty-three".