21856853 has 4 divisors (see below), whose sum is σ = 22164768. Its totient is φ = 21548940.

The previous prime is 21856847. The next prime is 21856867. The reversal of 21856853 is 35865812.

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 21856853 - 2⁴ = 21856837 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 (21856873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 153851 + ... + 153992.

It is an arithmetic number, because the mean of its divisors is an integer number (5541192).

Almost surely, 2^21856853 is an apocalyptic number.

It is an amenable number.

21856853 is a deficient number, since it is larger than the sum of its proper divisors (307915).

21856853 is an equidigital number, since it uses as much as digits as its factorization.

21856853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307914.

The product of its digits is 57600, while the sum is 38.

The square root of 21856853 is about 4675.1313350536. The cubic root of 21856853 is about 279.5948775602.

The spelling of 21856853 in words is "twenty-one million, eight hundred fifty-six thousand, eight hundred fifty-three".