21853851 has 4 divisors (see below), whose sum is σ = 29138472. Its totient is φ = 14569232.

The previous prime is 21853831. The next prime is 21853889. The reversal of 21853851 is 15835812.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21853851 - 2¹⁰ = 21852827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21853831) 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, 3642306 + ... + 3642311.

It is an arithmetic number, because the mean of its divisors is an integer number (7284618).

Almost surely, 2^21853851 is an apocalyptic number.

21853851 is a deficient number, since it is larger than the sum of its proper divisors (7284621).

21853851 is an equidigital number, since it uses as much as digits as its factorization.

21853851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7284620.

The product of its digits is 9600, while the sum is 33.

The square root of 21853851 is about 4674.8102635294. The cubic root of 21853851 is about 279.5820763539.

The spelling of 21853851 in words is "twenty-one million, eight hundred fifty-three thousand, eight hundred fifty-one".