81947756 has 48 divisors (see below), whose sum is σ = 163903488. Its totient is φ = 35510400.

The previous prime is 81947753. The next prime is 81947771. The reversal of 81947756 is 65774918.

It is a self number, because there is not a number n which added to its sum of digits gives 81947756.

It is not an unprimeable number, because it can be changed into a prime (81947753) 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, 99161 + ... + 99983.

It is an arithmetic number, because the mean of its divisors is an integer number (3414656).

Almost surely, 2^81947756 is an apocalyptic number.

It is a pronic number, being equal to 9052×9053.

It is an amenable number.

81947756 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

81947756 is a wasteful number, since it uses less digits than its factorization.

81947756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 942 (or 940 counting only the distinct ones).

The product of its digits is 423360, while the sum is 47.

The square root of 81947756 is about 9052.4999861917. The cubic root of 81947756 is about 434.3558634911.

The spelling of 81947756 in words is "eighty-one million, nine hundred forty-seven thousand, seven hundred fifty-six".