21121232123 has 12 divisors (see below), whose sum is σ = 22922447400. Its totient is φ = 19393931520.

The previous prime is 21121232113. The next prime is 21121232141. The reversal of 21121232123 is 32123212112.

It is not a de Polignac number, because 21121232123 - 2¹⁰ = 21121231099 is a prime.

It is a super-2 number, since 2×21121232123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121232095 and 21121232104.

It is not an unprimeable number, because it can be changed into a prime (21121232113) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 340973 + ... + 398126.

It is an arithmetic number, because the mean of its divisors is an integer number (1910203950).

Almost surely, 2^21121232123 is an apocalyptic number.

21121232123 is a deficient number, since it is larger than the sum of its proper divisors (1801215277).

21121232123 is an equidigital number, since it uses as much as digits as its factorization.

21121232123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 739198 (or 739157 counting only the distinct ones).

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

Adding to 21121232123 its reverse (32123212112), we get a palindrome (53244444235).

The spelling of 21121232123 in words is "twenty-one billion, one hundred twenty-one million, two hundred thirty-two thousand, one hundred twenty-three".