81751729 has 16 divisors (see below), whose sum is σ = 88095744. Its totient is φ = 75675600.

The previous prime is 81751711. The next prime is 81751777. The reversal of 81751729 is 92715718.

It is a cyclic number.

It is not a de Polignac number, because 81751729 - 2¹⁵ = 81718961 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81751691 and 81751700.

It is not an unprimeable number, because it can be changed into a prime (81751799) 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, 129244 + ... + 129874.

It is an arithmetic number, because the mean of its divisors is an integer number (5505984).

Almost surely, 2^81751729 is an apocalyptic number.

It is an amenable number.

81751729 is a deficient number, since it is larger than the sum of its proper divisors (6344015).

81751729 is a wasteful number, since it uses less digits than its factorization.

81751729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 828.

The product of its digits is 35280, while the sum is 40.

The square root of 81751729 is about 9041.6662734255. Note that the first 3 decimals coincide. The cubic root of 81751729 is about 434.0092464777.

The spelling of 81751729 in words is "eighty-one million, seven hundred fifty-one thousand, seven hundred twenty-nine".