221019809 has 2 divisors, whose sum is σ = 221019810. Its totient is φ = 221019808.

The previous prime is 221019797. The next prime is 221019829. The reversal of 221019809 is 908910122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142874209 + 78145600 = 11953^2 + 8840^2 .

It is a cyclic number.

It is not a de Polignac number, because 221019809 - 2⁴ = 221019793 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221019829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110509904 + 110509905.

It is an arithmetic number, because the mean of its divisors is an integer number (110509905).

Almost surely, 2^221019809 is an apocalyptic number.

It is an amenable number.

221019809 is a deficient number, since it is larger than the sum of its proper divisors (1).

221019809 is an equidigital number, since it uses as much as digits as its factorization.

221019809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 221019809 is about 14866.7349811584. The cubic root of 221019809 is about 604.6124230279.

The spelling of 221019809 in words is "two hundred twenty-one million, nineteen thousand, eight hundred nine".