21040031423 has 4 divisors (see below), whose sum is σ = 21174044520. Its totient is φ = 20906018328.

The previous prime is 21040031393. The next prime is 21040031429. The reversal of 21040031423 is 32413004012.

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-21040031423 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21040031395 and 21040031404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040031429) 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, 67006313 + ... + 67006626.

It is an arithmetic number, because the mean of its divisors is an integer number (5293511130).

Almost surely, 2^21040031423 is an apocalyptic number.

21040031423 is a deficient number, since it is larger than the sum of its proper divisors (134013097).

21040031423 is a wasteful number, since it uses less digits than its factorization.

21040031423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134013096.

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21040031423 its reverse (32413004012), we get a palindrome (53453035435).

The spelling of 21040031423 in words is "twenty-one billion, forty million, thirty-one thousand, four hundred twenty-three".