21203221123 has 4 divisors (see below), whose sum is σ = 24232252720. Its totient is φ = 18174189528.

The previous prime is 21203221103. The next prime is 21203221159. The reversal of 21203221123 is 32112230212.

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-21203221123 is a prime.

It is a super-2 number, since 2×21203221123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21203221123.

It is not an unprimeable number, because it can be changed into a prime (21203221103) 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, 1514515788 + ... + 1514515801.

It is an arithmetic number, because the mean of its divisors is an integer number (6058063180).

Almost surely, 2^21203221123 is an apocalyptic number.

21203221123 is a deficient number, since it is larger than the sum of its proper divisors (3029031597).

21203221123 is an equidigital number, since it uses as much as digits as its factorization.

21203221123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3029031596.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21203221123 its reverse (32112230212), we get a palindrome (53315451335).

The spelling of 21203221123 in words is "twenty-one billion, two hundred three million, two hundred twenty-one thousand, one hundred twenty-three".