21855253 has 4 divisors (see below), whose sum is σ = 24977440. Its totient is φ = 18733068.

The previous prime is 21855233. The next prime is 21855259. The reversal of 21855253 is 35255812.

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 21855253 - 2¹³ = 21847061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1561083 + ... + 1561096.

It is an arithmetic number, because the mean of its divisors is an integer number (6244360).

Almost surely, 2^21855253 is an apocalyptic number.

It is an amenable number.

21855253 is a deficient number, since it is larger than the sum of its proper divisors (3122187).

21855253 is an equidigital number, since it uses as much as digits as its factorization.

21855253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3122186.

The product of its digits is 12000, while the sum is 31.

The square root of 21855253 is about 4674.9602137344. The cubic root of 21855253 is about 279.5880549446.

The spelling of 21855253 in words is "twenty-one million, eight hundred fifty-five thousand, two hundred fifty-three".