21204233 has 4 divisors (see below), whose sum is σ = 21217428. Its totient is φ = 21191040.

The previous prime is 21204223. The next prime is 21204241. The reversal of 21204233 is 33240212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1026169 + 20178064 = 1013^2 + 4492^2 .

It is a cyclic number.

It is not a de Polignac number, because 21204233 - 2⁸ = 21203977 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21204223) 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, 3788 + ... + 7533.

It is an arithmetic number, because the mean of its divisors is an integer number (5304357).

Almost surely, 2^21204233 is an apocalyptic number.

It is an amenable number.

21204233 is a deficient number, since it is larger than the sum of its proper divisors (13195).

21204233 is a wasteful number, since it uses less digits than its factorization.

21204233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13194.

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

The square root of 21204233 is about 4604.8054247710. The cubic root of 21204233 is about 276.7839200748.

Adding to 21204233 its reverse (33240212), we get a palindrome (54444445).

The spelling of 21204233 in words is "twenty-one million, two hundred four thousand, two hundred thirty-three".