21351216223 has 4 divisors (see below), whose sum is σ = 21669891160. Its totient is φ = 21032541288.

The previous prime is 21351216217. The next prime is 21351216247. The reversal of 21351216223 is 32261215312.

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 21351216223 - 2⁵ = 21351216191 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21351216191 and 21351216200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21351216023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 159337368 + ... + 159337501.

It is an arithmetic number, because the mean of its divisors is an integer number (5417472790).

Almost surely, 2^21351216223 is an apocalyptic number.

21351216223 is a deficient number, since it is larger than the sum of its proper divisors (318674937).

21351216223 is an equidigital number, since it uses as much as digits as its factorization.

21351216223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 318674936.

The product of its digits is 4320, while the sum is 28.

The spelling of 21351216223 in words is "twenty-one billion, three hundred fifty-one million, two hundred sixteen thousand, two hundred twenty-three".