21121223123 has 24 divisors (see below), whose sum is σ = 28573417824. Its totient is φ = 15192080640.

The previous prime is 21121223119. The next prime is 21121223143. The reversal of 21121223123 is 32132212112.

It is not a de Polignac number, because 21121223123 - 2² = 21121223119 is a prime.

It is a super-2 number, since 2×21121223123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121223095 and 21121223104.

It is not an unprimeable number, because it can be changed into a prime (21121223143) 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 23 ways as a sum of consecutive naturals, for example, 948086 + ... + 970107.

It is an arithmetic number, because the mean of its divisors is an integer number (1190559076).

Almost surely, 2^21121223123 is an apocalyptic number.

21121223123 is a deficient number, since it is larger than the sum of its proper divisors (7452194701).

21121223123 is a wasteful number, since it uses less digits than its factorization.

21121223123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1918235 (or 1918224 counting only the distinct ones).

The product of its digits is 288, while the sum is 20.

Adding to 21121223123 its reverse (32132212112), we get a palindrome (53253435235).

The spelling of 21121223123 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-three thousand, one hundred twenty-three".