81316515 has 32 divisors (see below), whose sum is σ = 149031936. Its totient is φ = 37088640.

The previous prime is 81316481. The next prime is 81316567. The reversal of 81316515 is 51561318.

It is not a de Polignac number, because 81316515 - 2¹⁵ = 81283747 is a prime.

It is a super-2 number, since 2×81316515² = 13224751223490450, which contains 22 as substring.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 85945 + ... + 86885.

It is an arithmetic number, because the mean of its divisors is an integer number (4657248).

Almost surely, 2^81316515 is an apocalyptic number.

81316515 is a deficient number, since it is larger than the sum of its proper divisors (67715421).

81316515 is a wasteful number, since it uses less digits than its factorization.

81316515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1779.

The product of its digits is 3600, while the sum is 30.

The square root of 81316515 is about 9017.5670222073. The cubic root of 81316515 is about 433.2377109850.

The spelling of 81316515 in words is "eighty-one million, three hundred sixteen thousand, five hundred fifteen".