81087815 has 8 divisors (see below), whose sum is σ = 97378848. Its totient is φ = 64821280.

The previous prime is 81087779. The next prime is 81087817. The reversal of 81087815 is 51878018.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81087815 - 2¹⁰ = 81086791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81087817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2189 + ... + 12921.

It is an arithmetic number, because the mean of its divisors is an integer number (12172356).

Almost surely, 2^81087815 is an apocalyptic number.

81087815 is a deficient number, since it is larger than the sum of its proper divisors (16291033).

81087815 is a wasteful number, since it uses less digits than its factorization.

81087815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12249.

The product of its (nonzero) digits is 17920, while the sum is 38.

The square root of 81087815 is about 9004.8772895581. The cubic root of 81087815 is about 432.8311740608.

The spelling of 81087815 in words is "eighty-one million, eighty-seven thousand, eight hundred fifteen".