221002809 has 4 divisors (see below), whose sum is σ = 294670416. Its totient is φ = 147335204.

The previous prime is 221002799. The next prime is 221002861. The reversal of 221002809 is 908200122.

221002809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221002809 - 2⁷ = 221002681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221002709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36833799 + ... + 36833804.

It is an arithmetic number, because the mean of its divisors is an integer number (73667604).

Almost surely, 2^221002809 is an apocalyptic number.

It is an amenable number.

221002809 is a deficient number, since it is larger than the sum of its proper divisors (73667607).

221002809 is an equidigital number, since it uses as much as digits as its factorization.

221002809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73667606.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 221002809 is about 14866.1632239122. The cubic root of 221002809 is about 604.5969211372.

The spelling of 221002809 in words is "two hundred twenty-one million, two thousand, eight hundred nine".