21204123 has 8 divisors (see below), whose sum is σ = 28297728. Its totient is φ = 14123304.

The previous prime is 21204121. The next prime is 21204143. The reversal of 21204123 is 32140212.

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

It is not a de Polignac number, because 21204123 - 2¹ = 21204121 is a prime.

It is a super-2 number, since 2×21204123² = 899229664398258, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21204121) 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, 1786 + ... + 6752.

It is an arithmetic number, because the mean of its divisors is an integer number (3537216).

Almost surely, 2^21204123 is an apocalyptic number.

21204123 is a deficient number, since it is larger than the sum of its proper divisors (7093605).

21204123 is a wasteful number, since it uses less digits than its factorization.

21204123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6393.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21204123 is about 4604.7934807112. The cubic root of 21204123 is about 276.7834414552.

Adding to 21204123 its reverse (32140212), we get a palindrome (53344335).

The spelling of 21204123 in words is "twenty-one million, two hundred four thousand, one hundred twenty-three".