21234805 has 8 divisors (see below), whose sum is σ = 25804800. Its totient is φ = 16772496.

The previous prime is 21234797. The next prime is 21234809. The reversal of 21234805 is 50843212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21234805 - 2³ = 21234797 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21234805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21234809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26485 + ... + 27274.

It is an arithmetic number, because the mean of its divisors is an integer number (3225600).

Almost surely, 2^21234805 is an apocalyptic number.

It is an amenable number.

21234805 is a deficient number, since it is larger than the sum of its proper divisors (4569995).

21234805 is an equidigital number, since it uses as much as digits as its factorization.

21234805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53843.

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 21234805 is about 4608.1238047605. The cubic root of 21234805 is about 276.9168774036.

The spelling of 21234805 in words is "twenty-one million, two hundred thirty-four thousand, eight hundred five".