21853913 has 2 divisors, whose sum is σ = 21853914. Its totient is φ = 21853912.

The previous prime is 21853889. The next prime is 21853927. The reversal of 21853913 is 31935812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17372224 + 4481689 = 4168^2 + 2117^2 .

It is a cyclic number.

It is not a de Polignac number, because 21853913 - 2¹⁰ = 21852889 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21853913.

It is not a weakly prime, because it can be changed into another prime (21853213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10926956 + 10926957.

It is an arithmetic number, because the mean of its divisors is an integer number (10926957).

Almost surely, 2^21853913 is an apocalyptic number.

It is an amenable number.

21853913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21853913 is an equidigital number, since it uses as much as digits as its factorization.

21853913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 32.

The square root of 21853913 is about 4674.8168948099. The cubic root of 21853913 is about 279.5823407478.

The spelling of 21853913 in words is "twenty-one million, eight hundred fifty-three thousand, nine hundred thirteen".