20121221123 has 4 divisors (see below), whose sum is σ = 20996056848. Its totient is φ = 19246385400.

The previous prime is 20121221117. The next prime is 20121221129. The reversal of 20121221123 is 32112212102.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20121221117) and next prime (20121221129).

It is a cyclic number.

It is not a de Polignac number, because 20121221123 - 2²⁴ = 20104443907 is a prime.

It is a super-2 number, since 2×20121221123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20121221129) 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, 437417828 + ... + 437417873.

It is an arithmetic number, because the mean of its divisors is an integer number (5249014212).

Almost surely, 2^20121221123 is an apocalyptic number.

20121221123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

20121221123 is a deficient number, since it is larger than the sum of its proper divisors (874835725).

20121221123 is an equidigital number, since it uses as much as digits as its factorization.

20121221123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874835724.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 20121221123 its reverse (32112212102), we get a palindrome (52233433225).

The spelling of 20121221123 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty-three".