21213002123 has 4 divisors (see below), whose sum is σ = 21234408768. Its totient is φ = 21191595480.

The previous prime is 21213002117. The next prime is 21213002149. The reversal of 21213002123 is 32120031212.

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 21213002123 - 2¹⁸ = 21212739979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21213002623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10701836 + ... + 10703817.

It is an arithmetic number, because the mean of its divisors is an integer number (5308602192).

Almost surely, 2^21213002123 is an apocalyptic number.

21213002123 is a deficient number, since it is larger than the sum of its proper divisors (21406645).

21213002123 is an equidigital number, since it uses as much as digits as its factorization.

21213002123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21406644.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21213002123 its reverse (32120031212), we get a palindrome (53333033335).

The spelling of 21213002123 in words is "twenty-one billion, two hundred thirteen million, two thousand, one hundred twenty-three".