21420213123 has 8 divisors (see below), whose sum is σ = 29332183888. Its totient is φ = 13894192224.

The previous prime is 21420213119. The next prime is 21420213137. The reversal of 21420213123 is 32131202412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21420213123 - 2² = 21420213119 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 21420213123.

It is not an unprimeable number, because it can be changed into a prime (21420213173) 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 7 ways as a sum of consecutive naturals, for example, 96487336 + ... + 96487557.

It is an arithmetic number, because the mean of its divisors is an integer number (3666522986).

Almost surely, 2^21420213123 is an apocalyptic number.

21420213123 is a deficient number, since it is larger than the sum of its proper divisors (7911970765).

21420213123 is a wasteful number, since it uses less digits than its factorization.

21420213123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192974933.

The product of its (nonzero) digits is 576, while the sum is 21.

Adding to 21420213123 its reverse (32131202412), we get a palindrome (53551415535).

The spelling of 21420213123 in words is "twenty-one billion, four hundred twenty million, two hundred thirteen thousand, one hundred twenty-three".