221495809 has 2 divisors, whose sum is σ = 221495810. Its totient is φ = 221495808.

The previous prime is 221495803. The next prime is 221495849. The reversal of 221495809 is 908594122.

It is an a-pointer prime, because the next prime (221495849) can be obtained adding 221495809 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 132250000 + 89245809 = 11500^2 + 9447^2 .

It is a cyclic number.

It is not a de Polignac number, because 221495809 - 2⁵ = 221495777 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221495803) 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 as a sum of consecutive naturals, namely, 110747904 + 110747905.

It is an arithmetic number, because the mean of its divisors is an integer number (110747905).

Almost surely, 2^221495809 is an apocalyptic number.

It is an amenable number.

221495809 is a deficient number, since it is larger than the sum of its proper divisors (1).

221495809 is an equidigital number, since it uses as much as digits as its factorization.

221495809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 221495809 is about 14882.7352660726. The cubic root of 221495809 is about 605.0461536176.

The spelling of 221495809 in words is "two hundred twenty-one million, four hundred ninety-five thousand, eight hundred nine".