81366866 has 32 divisors (see below), whose sum is σ = 145722240. Its totient is φ = 33336576.

The previous prime is 81366839. The next prime is 81366871. The reversal of 81366866 is 66866318.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42506 + ... + 44378.

It is an arithmetic number, because the mean of its divisors is an integer number (4553820).

Almost surely, 2^81366866 is an apocalyptic number.

81366866 is a deficient number, since it is larger than the sum of its proper divisors (64355374).

81366866 is a wasteful number, since it uses less digits than its factorization.

81366866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2018.

The product of its digits is 248832, while the sum is 44.

The square root of 81366866 is about 9020.3584185996. The cubic root of 81366866 is about 433.3271124682.

The spelling of 81366866 in words is "eighty-one million, three hundred sixty-six thousand, eight hundred sixty-six".