21233405 has 4 divisors (see below), whose sum is σ = 25480092. Its totient is φ = 16986720.

The previous prime is 21233389. The next prime is 21233411. The reversal of 21233405 is 50433212.

It is a happy number.

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 8602489 + 12630916 = 2933^2 + 3554^2 .

It is not a de Polignac number, because 21233405 - 2⁴ = 21233389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2123336 + ... + 2123345.

It is an arithmetic number, because the mean of its divisors is an integer number (6370023).

Almost surely, 2^21233405 is an apocalyptic number.

It is an amenable number.

21233405 is a deficient number, since it is larger than the sum of its proper divisors (4246687).

21233405 is an equidigital number, since it uses as much as digits as its factorization.

21233405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4246686.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21233405 is about 4607.9718966157. The cubic root of 21233405 is about 276.9107916064.

Adding to 21233405 its reverse (50433212), we get a palindrome (71666617).

The spelling of 21233405 in words is "twenty-one million, two hundred thirty-three thousand, four hundred five".