21002003423 has 4 divisors (see below), whose sum is σ = 21015563400. Its totient is φ = 20988443448.

The previous prime is 21002003401. The next prime is 21002003431. The reversal of 21002003423 is 32430020012.

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-21002003423 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002003123) 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, 6777665 + ... + 6780762.

It is an arithmetic number, because the mean of its divisors is an integer number (5253890850).

Almost surely, 2^21002003423 is an apocalyptic number.

21002003423 is a deficient number, since it is larger than the sum of its proper divisors (13559977).

21002003423 is a wasteful number, since it uses less digits than its factorization.

21002003423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13559976.

The product of its (nonzero) digits is 288, while the sum is 17.

Adding to 21002003423 its reverse (32430020012), we get a palindrome (53432023435).

The spelling of 21002003423 in words is "twenty-one billion, two million, three thousand, four hundred twenty-three".