21221011123 has 4 divisors (see below), whose sum is σ = 22853396608. Its totient is φ = 19588625640.

The previous prime is 21221011079. The next prime is 21221011127. The reversal of 21221011123 is 32111012212.

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 21221011123 - 2⁹ = 21221010611 is a prime.

It is a super-2 number, since 2×21221011123² (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 = 21221011097 and 21221011106.

It is not an unprimeable number, because it can be changed into a prime (21221011127) 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, 816192723 + ... + 816192748.

It is an arithmetic number, because the mean of its divisors is an integer number (5713349152).

Almost surely, 2^21221011123 is an apocalyptic number.

21221011123 is a deficient number, since it is larger than the sum of its proper divisors (1632385485).

21221011123 is a wasteful number, since it uses less digits than its factorization.

21221011123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632385484.

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

Adding to 21221011123 its reverse (32111012212), we get a palindrome (53332023335).

The spelling of 21221011123 in words is "twenty-one billion, two hundred twenty-one million, eleven thousand, one hundred twenty-three".