81813715 has 16 divisors (see below), whose sum is σ = 105300000. Its totient is φ = 60832512.

The previous prime is 81813703. The next prime is 81813731. The reversal of 81813715 is 51731818.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81813715 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3090 + ... + 13159.

It is an arithmetic number, because the mean of its divisors is an integer number (6581250).

Almost surely, 2^81813715 is an apocalyptic number.

81813715 is a deficient number, since it is larger than the sum of its proper divisors (23486285).

81813715 is a wasteful number, since it uses less digits than its factorization.

81813715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16326.

The product of its digits is 6720, while the sum is 34.

The square root of 81813715 is about 9045.0934212975. The cubic root of 81813715 is about 434.1189106238.

It can be divided in two parts, 81813 and 715, that added together give a palindrome (82528).

The spelling of 81813715 in words is "eighty-one million, eight hundred thirteen thousand, seven hundred fifteen".