811942509 has 16 divisors (see below), whose sum is σ = 1239372288. Its totient is φ = 463169712.

The previous prime is 811942501. The next prime is 811942519. The reversal of 811942509 is 905249118.

It is not a de Polignac number, because 811942509 - 2³ = 811942501 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811942501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20607 + ... + 45260.

It is an arithmetic number, because the mean of its divisors is an integer number (77460768).

Almost surely, 2^811942509 is an apocalyptic number.

It is an amenable number.

811942509 is a deficient number, since it is larger than the sum of its proper divisors (427429779).

811942509 is a wasteful number, since it uses less digits than its factorization.

811942509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66464.

The product of its (nonzero) digits is 25920, while the sum is 39.

The square root of 811942509 is about 28494.6049104037. The cubic root of 811942509 is about 932.9143207451.

The spelling of 811942509 in words is "eight hundred eleven million, nine hundred forty-two thousand, five hundred nine".