840221809 has 12 divisors (see below), whose sum is σ = 1003823296. Its totient is φ = 688874472.

The previous prime is 840221777. The next prime is 840221831. The reversal of 840221809 is 908122048.

It is not a de Polignac number, because 840221809 - 2⁵ = 840221777 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (840221009) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 109749 + ... + 117154.

Almost surely, 2^840221809 is an apocalyptic number.

It is an amenable number.

840221809 is a deficient number, since it is larger than the sum of its proper divisors (163601487).

840221809 is a wasteful number, since it uses less digits than its factorization.

840221809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226956 (or 226933 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 840221809 is about 28986.5798085942. The cubic root of 840221809 is about 943.6218385150.

The spelling of 840221809 in words is "eight hundred forty million, two hundred twenty-one thousand, eight hundred nine".