21120121123 has 4 divisors (see below), whose sum is σ = 21170527560. Its totient is φ = 21069714688.

The previous prime is 21120121091. The next prime is 21120121129. The reversal of 21120121123 is 32112102112.

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 21120121123 - 2⁵ = 21120121091 is a prime.

It is a super-2 number, since 2×21120121123² (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 = 21120121097 and 21120121106.

It is not an unprimeable number, because it can be changed into a prime (21120121129) 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, 25202590 + ... + 25203427.

It is an arithmetic number, because the mean of its divisors is an integer number (5292631890).

Almost surely, 2^21120121123 is an apocalyptic number.

21120121123 is a deficient number, since it is larger than the sum of its proper divisors (50406437).

21120121123 is an equidigital number, since it uses as much as digits as its factorization.

21120121123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50406436.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21120121123 its reverse (32112102112), we get a palindrome (53232223235).

It can be divided in two parts, 211201 and 21123, that added together give a square (232324 = 482²).

The spelling of 21120121123 in words is "twenty-one billion, one hundred twenty million, one hundred twenty-one thousand, one hundred twenty-three".