81287805 has 16 divisors (see below), whose sum is σ = 130546944. Its totient is φ = 43191360.

The previous prime is 81287677. The next prime is 81287837. The reversal of 81287805 is 50878218.

It is not a de Polignac number, because 81287805 - 2⁷ = 81287677 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5934 + ... + 14063.

It is an arithmetic number, because the mean of its divisors is an integer number (8159184).

Almost surely, 2^81287805 is an apocalyptic number.

It is an amenable number.

81287805 is a deficient number, since it is larger than the sum of its proper divisors (49259139).

81287805 is a wasteful number, since it uses less digits than its factorization.

81287805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20276.

The product of its (nonzero) digits is 35840, while the sum is 39.

The square root of 81287805 is about 9015.9749888739. The cubic root of 81287805 is about 433.1867179864.

The spelling of 81287805 in words is "eighty-one million, two hundred eighty-seven thousand, eight hundred five".