21853945 has 4 divisors (see below), whose sum is σ = 26224740. Its totient is φ = 17483152.

The previous prime is 21853927. The next prime is 21853961. The reversal of 21853945 is 54935812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12138256 + 9715689 = 3484^2 + 3117^2 .

It is a cyclic number.

It is not a de Polignac number, because 21853945 - 2⁵ = 21853913 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2185390 + ... + 2185399.

It is an arithmetic number, because the mean of its divisors is an integer number (6556185).

Almost surely, 2^21853945 is an apocalyptic number.

It is an amenable number.

21853945 is a deficient number, since it is larger than the sum of its proper divisors (4370795).

21853945 is an equidigital number, since it uses as much as digits as its factorization.

21853945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4370794.

The product of its digits is 43200, while the sum is 37.

The square root of 21853945 is about 4674.8203174026. The cubic root of 21853945 is about 279.5824772090.

The spelling of 21853945 in words is "twenty-one million, eight hundred fifty-three thousand, nine hundred forty-five".