21873217 has 2 divisors, whose sum is σ = 21873218. Its totient is φ = 21873216.

The previous prime is 21873191. The next prime is 21873233. The reversal of 21873217 is 71237812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12082576 + 9790641 = 3476^2 + 3129^2 .

It is a cyclic number.

It is not a de Polignac number, because 21873217 - 2¹¹ = 21871169 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21873277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10936608 + 10936609.

It is an arithmetic number, because the mean of its divisors is an integer number (10936609).

Almost surely, 2^21873217 is an apocalyptic number.

It is an amenable number.

21873217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21873217 is an equidigital number, since it uses as much as digits as its factorization.

21873217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4704, while the sum is 31.

The square root of 21873217 is about 4676.8811188654. The cubic root of 21873217 is about 279.6646367524.

The spelling of 21873217 in words is "twenty-one million, eight hundred seventy-three thousand, two hundred seventeen".