8921809 has 4 divisors (see below), whose sum is σ = 9608116. Its totient is φ = 8235504.

The previous prime is 8921791. The next prime is 8921833. The reversal of 8921809 is 9081298.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5107600 + 3814209 = 2260^2 + 1953^2 .

It is a cyclic number.

It is not a de Polignac number, because 8921809 - 2⁵ = 8921777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8921609) 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, 343134 + ... + 343159.

It is an arithmetic number, because the mean of its divisors is an integer number (2402029).

Almost surely, 2^8921809 is an apocalyptic number.

It is an amenable number.

8921809 is a deficient number, since it is larger than the sum of its proper divisors (686307).

8921809 is a wasteful number, since it uses less digits than its factorization.

8921809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686306.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 8921809 is about 2986.9397382605. The cubic root of 8921809 is about 207.4042447816.

It can be divided in two parts, 8921 and 809, that added together give a triangular number (9730 = T₁₃₉).

The spelling of 8921809 in words is "eight million, nine hundred twenty-one thousand, eight hundred nine".