21011332123 has 4 divisors (see below), whose sum is σ = 21020159088. Its totient is φ = 21002505160.

The previous prime is 21011332081. The next prime is 21011332129. The reversal of 21011332123 is 32123311012.

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 21011332123 - 2²⁹ = 20474461211 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 21011332123.

It is not an unprimeable number, because it can be changed into a prime (21011332129) 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, 4409911 + ... + 4414672.

It is an arithmetic number, because the mean of its divisors is an integer number (5255039772).

Almost surely, 2^21011332123 is an apocalyptic number.

21011332123 is a deficient number, since it is larger than the sum of its proper divisors (8826965).

21011332123 is an equidigital number, since it uses as much as digits as its factorization.

21011332123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8826964.

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 21011332123 its reverse (32123311012), we get a palindrome (53134643135).

The spelling of 21011332123 in words is "twenty-one billion, eleven million, three hundred thirty-two thousand, one hundred twenty-three".