21030123 has 4 divisors (see below), whose sum is σ = 28040168. Its totient is φ = 14020080.

The previous prime is 21030109. The next prime is 21030127. The reversal of 21030123 is 32103012.

It is a happy number.

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

It is not a de Polignac number, because 21030123 - 2¹⁷ = 20899051 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21030099 and 21030108.

It is not an unprimeable number, because it can be changed into a prime (21030127) 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, 3505018 + ... + 3505023.

It is an arithmetic number, because the mean of its divisors is an integer number (7010042).

Almost surely, 2^21030123 is an apocalyptic number.

21030123 is a deficient number, since it is larger than the sum of its proper divisors (7010045).

21030123 is an equidigital number, since it uses as much as digits as its factorization.

21030123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7010044.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21030123 is about 4585.8612059241. The cubic root of 21030123 is about 276.0242706025.

Adding to 21030123 its reverse (32103012), we get a palindrome (53133135).

It can be divided in two parts, 2103012 and 3, that multiplied together give a palindrome (6309036).

The spelling of 21030123 in words is "twenty-one million, thirty thousand, one hundred twenty-three".