81087809 has 16 divisors (see below), whose sum is σ = 91010304. Its totient is φ = 71610000.

The previous prime is 81087779. The next prime is 81087817. The reversal of 81087809 is 90878018.

It is not a de Polignac number, because 81087809 - 2⁸ = 81087553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81087859) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 118382 + ... + 119064.

It is an arithmetic number, because the mean of its divisors is an integer number (5688144).

Almost surely, 2^81087809 is an apocalyptic number.

It is an amenable number.

81087809 is a deficient number, since it is larger than the sum of its proper divisors (9922495).

81087809 is a wasteful number, since it uses less digits than its factorization.

81087809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988.

The product of its (nonzero) digits is 32256, while the sum is 41.

The square root of 81087809 is about 9004.8769564053. The cubic root of 81087809 is about 432.8311633852.

The spelling of 81087809 in words is "eighty-one million, eighty-seven thousand, eight hundred nine".