21142405423 has 4 divisors (see below), whose sum is σ = 21152413408. Its totient is φ = 21132397440.

The previous prime is 21142405397. The next prime is 21142405481. The reversal of 21142405423 is 32450424112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21142405423 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21142405391 and 21142405400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21142405523) 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, 5000823 + ... + 5005048.

It is an arithmetic number, because the mean of its divisors is an integer number (5288103352).

Almost surely, 2^21142405423 is an apocalyptic number.

21142405423 is a deficient number, since it is larger than the sum of its proper divisors (10007985).

21142405423 is a wasteful number, since it uses less digits than its factorization.

21142405423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10007984.

The product of its (nonzero) digits is 7680, while the sum is 28.

Adding to 21142405423 its reverse (32450424112), we get a palindrome (53592829535).

The spelling of 21142405423 in words is "twenty-one billion, one hundred forty-two million, four hundred five thousand, four hundred twenty-three".