820755081 has 24 divisors (see below), whose sum is σ = 1200724200. Its totient is φ = 540205056.

The previous prime is 820755079. The next prime is 820755139. The reversal of 820755081 is 180557028.

820755081 is a `hidden beast` number, since 8 + 20 + 7 + 550 + 81 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 2509056 + 818246025 = 1584^2 + 28605^2 .

It is not a de Polignac number, because 820755081 - 2¹ = 820755079 is a prime.

It is a super-2 number, since 2×820755081² = 1347277805974633122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (820755011) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 236245 + ... + 239693.

It is an arithmetic number, because the mean of its divisors is an integer number (50030175).

Almost surely, 2^820755081 is an apocalyptic number.

It is an amenable number.

820755081 is a deficient number, since it is larger than the sum of its proper divisors (379969119).

820755081 is a wasteful number, since it uses less digits than its factorization.

820755081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3785 (or 3782 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 820755081 is about 28648.8233789802. The cubic root of 820755081 is about 936.2773702681.

The spelling of 820755081 in words is "eight hundred twenty million, seven hundred fifty-five thousand, eighty-one".