81756147 has 32 divisors (see below), whose sum is σ = 122204160. Its totient is φ = 48201120.

The previous prime is 81756139. The next prime is 81756149. The reversal of 81756147 is 74165718.

It is not a de Polignac number, because 81756147 - 2³ = 81756139 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81756149) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 227554 + ... + 227912.

It is an arithmetic number, because the mean of its divisors is an integer number (3818880).

Almost surely, 2^81756147 is an apocalyptic number.

81756147 is a deficient number, since it is larger than the sum of its proper divisors (40448013).

81756147 is a wasteful number, since it uses less digits than its factorization.

81756147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 543.

The product of its digits is 47040, while the sum is 39.

The square root of 81756147 is about 9041.9105834995. The cubic root of 81756147 is about 434.0170645318.

The spelling of 81756147 in words is "eighty-one million, seven hundred fifty-six thousand, one hundred forty-seven".