21121100123 has 16 divisors (see below), whose sum is σ = 22877392896. Its totient is φ = 19448737440.

The previous prime is 21121100107. The next prime is 21121100129. The reversal of 21121100123 is 32100112112.

It is not a de Polignac number, because 21121100123 - 2⁴ = 21121100107 is a prime.

It is a super-2 number, since 2×21121100123² (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 = 21121100098 and 21121100107.

It is not an unprimeable number, because it can be changed into a prime (21121100129) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 94211 + ... + 226092.

It is an arithmetic number, because the mean of its divisors is an integer number (1429837056).

Almost surely, 2^21121100123 is an apocalyptic number.

21121100123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21121100123 is a deficient number, since it is larger than the sum of its proper divisors (1756292773).

21121100123 is a wasteful number, since it uses less digits than its factorization.

21121100123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320434.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21121100123 its reverse (32100112112), we get a palindrome (53221212235).

The spelling of 21121100123 in words is "twenty-one billion, one hundred twenty-one million, one hundred thousand, one hundred twenty-three".