80565781 has 4 divisors (see below), whose sum is σ = 81363564. Its totient is φ = 79768000.

The previous prime is 80565773. The next prime is 80565787. The reversal of 80565781 is 18756508.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 69872881 + 10692900 = 8359^2 + 3270^2 .

It is a cyclic number.

It is not a de Polignac number, because 80565781 - 2³ = 80565773 is a prime.

It is a super-2 number, since 2×80565781² = 12981690136279922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (80565787) 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 3 ways as a sum of consecutive naturals, for example, 398740 + ... + 398941.

It is an arithmetic number, because the mean of its divisors is an integer number (20340891).

Almost surely, 2^80565781 is an apocalyptic number.

It is an amenable number.

80565781 is a deficient number, since it is larger than the sum of its proper divisors (797783).

80565781 is a wasteful number, since it uses less digits than its factorization.

80565781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 797782.

The product of its (nonzero) digits is 67200, while the sum is 40.

The square root of 80565781 is about 8975.8443056907. The cubic root of 80565781 is about 431.9003345900.

The spelling of 80565781 in words is "eighty million, five hundred sixty-five thousand, seven hundred eighty-one".