81308715 has 16 divisors (see below), whose sum is σ = 131359488. Its totient is φ = 42942816.

The previous prime is 81308713. The next prime is 81308723. The reversal of 81308715 is 51780318.

It is not a de Polignac number, because 81308715 - 2¹ = 81308713 is a prime.

It is a super-2 number, since 2×81308715² = 13222214269902450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81308713) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 24769 + ... + 27858.

It is an arithmetic number, because the mean of its divisors is an integer number (8209968).

Almost surely, 2^81308715 is an apocalyptic number.

81308715 is a deficient number, since it is larger than the sum of its proper divisors (50050773).

81308715 is a wasteful number, since it uses less digits than its factorization.

81308715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52738.

The product of its (nonzero) digits is 6720, while the sum is 33.

The square root of 81308715 is about 9017.1345226740. The cubic root of 81308715 is about 433.2238582754.

The spelling of 81308715 in words is "eighty-one million, three hundred eight thousand, seven hundred fifteen".