21200123 has 16 divisors (see below), whose sum is σ = 24879360. Its totient is φ = 17690400.

The previous prime is 21200117. The next prime is 21200129. The reversal of 21200123 is 32100212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21200117) and next prime (21200129).

It is not a de Polignac number, because 21200123 - 2²² = 17005819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21200129) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55748 + ... + 56126.

It is an arithmetic number, because the mean of its divisors is an integer number (1554960).

Almost surely, 2^21200123 is an apocalyptic number.

21200123 is a deficient number, since it is larger than the sum of its proper divisors (3679237).

21200123 is a wasteful number, since it uses less digits than its factorization.

21200123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 578.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21200123 is about 4604.3591302156. The cubic root of 21200123 is about 276.7660359819.

Adding to 21200123 its reverse (32100212), we get a palindrome (53300335).

The spelling of 21200123 in words is "twenty-one million, two hundred thousand, one hundred twenty-three".