21112021123 has 4 divisors (see below), whose sum is σ = 21113943280. Its totient is φ = 21110098968.

The previous prime is 21112021111. The next prime is 21112021157. The reversal of 21112021123 is 32112021112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112021123 is a prime.

It is a super-2 number, since 2×21112021123² (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 = 21112021097 and 21112021106.

It is not an unprimeable number, because it can be changed into a prime (21112021193) 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, 944508 + ... + 966601.

It is an arithmetic number, because the mean of its divisors is an integer number (5278485820).

Almost surely, 2^21112021123 is an apocalyptic number.

21112021123 is a deficient number, since it is larger than the sum of its proper divisors (1922157).

21112021123 is a wasteful number, since it uses less digits than its factorization.

21112021123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1922156.

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

Adding to 21112021123 its reverse (32112021112), we get a palindrome (53224042235).

The spelling of 21112021123 in words is "twenty-one billion, one hundred twelve million, twenty-one thousand, one hundred twenty-three".