21234305 has 16 divisors (see below), whose sum is σ = 27155520. Its totient is φ = 15893568.

The previous prime is 21234299. The next prime is 21234307. The reversal of 21234305 is 50343212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21234305 - 2⁸ = 21234049 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21234307) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6539 + ... + 9231.

It is an arithmetic number, because the mean of its divisors is an integer number (1697220).

Almost surely, 2^21234305 is an apocalyptic number.

It is an amenable number.

21234305 is a deficient number, since it is larger than the sum of its proper divisors (5921215).

21234305 is a wasteful number, since it uses less digits than its factorization.

21234305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2800.

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

The square root of 21234305 is about 4608.0695524265. The cubic root of 21234305 is about 276.9147039353.

Adding to 21234305 its reverse (50343212), we get a palindrome (71577517).

The spelling of 21234305 in words is "twenty-one million, two hundred thirty-four thousand, three hundred five".