21420103123 has 4 divisors (see below), whose sum is σ = 21439178248. Its totient is φ = 21401028000.

The previous prime is 21420103057. The next prime is 21420103127. The reversal of 21420103123 is 32130102412.

It is a happy number.

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 21420103123 - 2⁹ = 21420102611 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 21420103123.

It is not an unprimeable number, because it can be changed into a prime (21420103127) 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, 9535878 + ... + 9538123.

It is an arithmetic number, because the mean of its divisors is an integer number (5359794562).

Almost surely, 2^21420103123 is an apocalyptic number.

21420103123 is a deficient number, since it is larger than the sum of its proper divisors (19075125).

21420103123 is a wasteful number, since it uses less digits than its factorization.

21420103123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19075124.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21420103123 its reverse (32130102412), we get a palindrome (53550205535).

The spelling of 21420103123 in words is "twenty-one billion, four hundred twenty million, one hundred three thousand, one hundred twenty-three".