21220433 has 4 divisors (see below), whose sum is σ = 22852788. Its totient is φ = 19588080.

The previous prime is 21220429. The next prime is 21220477. The reversal of 21220433 is 33402212.

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 12623809 + 8596624 = 3553^2 + 2932^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220433 - 2² = 21220429 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 816158 + ... + 816183.

It is an arithmetic number, because the mean of its divisors is an integer number (5713197).

Almost surely, 2^21220433 is an apocalyptic number.

It is an amenable number.

21220433 is a deficient number, since it is larger than the sum of its proper divisors (1632355).

21220433 is a wasteful number, since it uses less digits than its factorization.

21220433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1632354.

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

The square root of 21220433 is about 4606.5641209040. The cubic root of 21220433 is about 276.8543896219.

Adding to 21220433 its reverse (33402212), we get a palindrome (54622645).

The spelling of 21220433 in words is "twenty-one million, two hundred twenty thousand, four hundred thirty-three".