81147666 has 32 divisors (see below), whose sum is σ = 165242880. Its totient is φ = 26562816.

The previous prime is 81147641. The next prime is 81147667. The reversal of 81147666 is 66674118.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81147667) 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, 82570 + ... + 83546.

It is an arithmetic number, because the mean of its divisors is an integer number (5163840).

Almost surely, 2^81147666 is an apocalyptic number.

81147666 is an abundant number, since it is smaller than the sum of its proper divisors (84095214).

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

81147666 is a wasteful number, since it uses less digits than its factorization.

81147666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1218.

The product of its digits is 48384, while the sum is 39.

The square root of 81147666 is about 9008.1999311738. The cubic root of 81147666 is about 432.9376389167.

The spelling of 81147666 in words is "eighty-one million, one hundred forty-seven thousand, six hundred sixty-six".