21284233 has 4 divisors (see below), whose sum is σ = 21394708. Its totient is φ = 21173760.

The previous prime is 21284227. The next prime is 21284243. The reversal of 21284233 is 33248212.

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 5626384 + 15657849 = 2372^2 + 3957^2 .

It is a cyclic number.

It is not a de Polignac number, because 21284233 - 2⁹ = 21283721 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21284198 and 21284207.

It is not an unprimeable number, because it can be changed into a prime (21284243) 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, 54948 + ... + 55333.

It is an arithmetic number, because the mean of its divisors is an integer number (5348677).

Almost surely, 2^21284233 is an apocalyptic number.

It is an amenable number.

21284233 is a deficient number, since it is larger than the sum of its proper divisors (110475).

21284233 is a wasteful number, since it uses less digits than its factorization.

21284233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110474.

The product of its digits is 2304, while the sum is 25.

The square root of 21284233 is about 4613.4838246167. The cubic root of 21284233 is about 277.1315696049.

The spelling of 21284233 in words is "twenty-one million, two hundred eighty-four thousand, two hundred thirty-three".