21210233 has 4 divisors (see below), whose sum is σ = 23138448. Its totient is φ = 19282020.

The previous prime is 21210227. The next prime is 21210269. The reversal of 21210233 is 33201212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21210233 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 (21210283) 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, 964091 + ... + 964112.

It is an arithmetic number, because the mean of its divisors is an integer number (5784612).

Almost surely, 2^21210233 is an apocalyptic number.

It is an amenable number.

21210233 is a deficient number, since it is larger than the sum of its proper divisors (1928215).

21210233 is a wasteful number, since it uses less digits than its factorization.

21210233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1928214.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21210233 is about 4605.4568720161. The cubic root of 21210233 is about 276.8100240907.

Adding to 21210233 its reverse (33201212), we get a palindrome (54411445).

The spelling of 21210233 in words is "twenty-one million, two hundred ten thousand, two hundred thirty-three".