21241855 has 4 divisors (see below), whose sum is σ = 25490232. Its totient is φ = 16993480.

The previous prime is 21241849. The next prime is 21241859. The reversal of 21241855 is 55814212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21241855 - 2⁹ = 21241343 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 (21241859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2124181 + ... + 2124190.

It is an arithmetic number, because the mean of its divisors is an integer number (6372558).

Almost surely, 2^21241855 is an apocalyptic number.

21241855 is a deficient number, since it is larger than the sum of its proper divisors (4248377).

21241855 is an equidigital number, since it uses as much as digits as its factorization.

21241855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4248376.

The product of its digits is 3200, while the sum is 28.

The square root of 21241855 is about 4608.8886946855. Note that the first 3 decimals coincide. The cubic root of 21241855 is about 276.9475196749.

The spelling of 21241855 in words is "twenty-one million, two hundred forty-one thousand, eight hundred fifty-five".