21202112123 has 4 divisors (see below), whose sum is σ = 21308655600. Its totient is φ = 21095568648.

The previous prime is 21202112101. The next prime is 21202112153. The reversal of 21202112123 is 32121120212.

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 21202112123 - 2²⁸ = 20933676667 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21202112153) 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, 53271440 + ... + 53271837.

It is an arithmetic number, because the mean of its divisors is an integer number (5327163900).

Almost surely, 2^21202112123 is an apocalyptic number.

21202112123 is a deficient number, since it is larger than the sum of its proper divisors (106543477).

21202112123 is a wasteful number, since it uses less digits than its factorization.

21202112123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106543476.

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

Adding to 21202112123 its reverse (32121120212), we get a palindrome (53323232335).

The spelling of 21202112123 in words is "twenty-one billion, two hundred two million, one hundred twelve thousand, one hundred twenty-three".