81775866 has 16 divisors (see below), whose sum is σ = 164376000. Its totient is φ = 27121248.

The previous prime is 81775801. The next prime is 81775871. The reversal of 81775866 is 66857718.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33051 + ... + 35438.

It is an arithmetic number, because the mean of its divisors is an integer number (10273500).

Almost surely, 2^81775866 is an apocalyptic number.

81775866 is an abundant number, since it is smaller than the sum of its proper divisors (82600134).

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

81775866 is a wasteful number, since it uses less digits than its factorization.

81775866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68693.

The product of its digits is 564480, while the sum is 48.

The square root of 81775866 is about 9043.0009399535. Note that the first 3 decimals coincide. The cubic root of 81775866 is about 434.0519556677.

The spelling of 81775866 in words is "eighty-one million, seven hundred seventy-five thousand, eight hundred sixty-six".