21805053 has 4 divisors (see below), whose sum is σ = 29073408. Its totient is φ = 14536700.

The previous prime is 21805037. The next prime is 21805073. The reversal of 21805053 is 35050812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21805053 - 2⁴ = 21805037 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21805073) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3634173 + ... + 3634178.

It is an arithmetic number, because the mean of its divisors is an integer number (7268352).

Almost surely, 2^21805053 is an apocalyptic number.

It is an amenable number.

21805053 is a deficient number, since it is larger than the sum of its proper divisors (7268355).

21805053 is an equidigital number, since it uses as much as digits as its factorization.

21805053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7268354.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21805053 is about 4669.5880974664. The cubic root of 21805053 is about 279.3738260489.

Adding to 21805053 its reverse (35050812), we get a palindrome (56855865).

The spelling of 21805053 in words is "twenty-one million, eight hundred five thousand, fifty-three".