809805749 has 4 divisors (see below), whose sum is σ = 818904780. Its totient is φ = 800706720.

The previous prime is 809805697. The next prime is 809805757. The reversal of 809805749 is 947508908.

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 153933649 + 655872100 = 12407^2 + 25610^2 .

It is a cyclic number.

It is not a de Polignac number, because 809805749 - 2¹² = 809801653 is a prime.

It is a super-2 number, since 2×809805749² = 1311570702226902002, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 809805697 and 809805706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809805769) 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, 4549382 + ... + 4549559.

It is an arithmetic number, because the mean of its divisors is an integer number (204726195).

Almost surely, 2^809805749 is an apocalyptic number.

809805749 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

It is an amenable number.

809805749 is a deficient number, since it is larger than the sum of its proper divisors (9099031).

809805749 is an equidigital number, since it uses as much as digits as its factorization.

809805749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9099030.

The product of its (nonzero) digits is 725760, while the sum is 50.

The square root of 809805749 is about 28457.0860946795. The cubic root of 809805749 is about 932.0952294062.

The spelling of 809805749 in words is "eight hundred nine million, eight hundred five thousand, seven hundred forty-nine".