81689718 has 32 divisors (see below), whose sum is σ = 180247680. Its totient is φ = 24474560.

The previous prime is 81689717. The next prime is 81689737. The reversal of 81689718 is 81798618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1080 + ... + 12827.

It is an arithmetic number, because the mean of its divisors is an integer number (5632740).

Almost surely, 2^81689718 is an apocalyptic number.

81689718 is an abundant number, since it is smaller than the sum of its proper divisors (98557962).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81689718 is a wasteful number, since it uses less digits than its factorization.

81689718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14012.

The product of its digits is 193536, while the sum is 48.

The square root of 81689718 is about 9038.2364430236. The cubic root of 81689718 is about 433.8994826215.

Subtracting 81689718 from its reverse (81798618), we obtain a square (108900 = 330²).

The spelling of 81689718 in words is "eighty-one million, six hundred eighty-nine thousand, seven hundred eighteen".