21011121220123 has 4 divisors (see below), whose sum is σ = 21011218067520. Its totient is φ = 21011024372728.

The previous prime is 21011121220099. The next prime is 21011121220129. The reversal of 21011121220123 is 32102212111012.

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 21011121220123 - 2⁵ = 21011121220091 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21011121220123.

It is not an unprimeable number, because it can be changed into a prime (21011121220129) 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 3 ways as a sum of consecutive naturals, for example, 48097540 + ... + 48532417.

It is an arithmetic number, because the mean of its divisors is an integer number (5252804516880).

Almost surely, 2^{21011121220123} is an apocalyptic number.

21011121220123 is a deficient number, since it is larger than the sum of its proper divisors (96847397).

21011121220123 is an equidigital number, since it uses as much as digits as its factorization.

21011121220123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96847396.

The product of its (nonzero) digits is 96, while the sum is 19.

Adding to 21011121220123 its reverse (32102212111012), we get a palindrome (53113333331135).

The spelling of 21011121220123 in words is "twenty-one trillion, eleven billion, one hundred twenty-one million, two hundred twenty thousand, one hundred twenty-three".