81565918 has 8 divisors (see below), whose sum is σ = 139827312. Its totient is φ = 34956816.

The previous prime is 81565903. The next prime is 81565961. The reversal of 81565918 is 81956518.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2913055 + ... + 2913082.

It is an arithmetic number, because the mean of its divisors is an integer number (17478414).

Almost surely, 2^81565918 is an apocalyptic number.

81565918 is a deficient number, since it is larger than the sum of its proper divisors (58261394).

81565918 is a wasteful number, since it uses less digits than its factorization.

81565918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5826146.

The product of its digits is 86400, while the sum is 43.

The square root of 81565918 is about 9031.3851650785. The cubic root of 81565918 is about 433.6801816050.

The spelling of 81565918 in words is "eighty-one million, five hundred sixty-five thousand, nine hundred eighteen".