21403123 has 8 divisors (see below), whose sum is σ = 24533600. Its totient is φ = 18290880.

The previous prime is 21403117. The next prime is 21403159. The reversal of 21403123 is 32130412.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21403123 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21403097 and 21403106.

It is not an unprimeable number, because it can be changed into a prime (21401123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1938 + ... + 6823.

It is an arithmetic number, because the mean of its divisors is an integer number (3066700).

Almost surely, 2^21403123 is an apocalyptic number.

21403123 is a deficient number, since it is larger than the sum of its proper divisors (3130477).

21403123 is an equidigital number, since it uses as much as digits as its factorization.

21403123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9117.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21403123 is about 4626.3509378343. The cubic root of 21403123 is about 277.6466146213.

Adding to 21403123 its reverse (32130412), we get a palindrome (53533535).

The spelling of 21403123 in words is "twenty-one million, four hundred three thousand, one hundred twenty-three".