820413581 has 4 divisors (see below), whose sum is σ = 883522332. Its totient is φ = 757304832.

The previous prime is 820413577. The next prime is 820413589. The reversal of 820413581 is 185314028.

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 218152900 + 602260681 = 14770^2 + 24541^2 .

It is a cyclic number.

It is not a de Polignac number, because 820413581 - 2² = 820413577 is a prime.

It is a super-2 number, since 2×820413581² = 1346156887778487122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820413589) 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, 31554356 + ... + 31554381.

It is an arithmetic number, because the mean of its divisors is an integer number (220880583).

Almost surely, 2^820413581 is an apocalyptic number.

It is an amenable number.

820413581 is a deficient number, since it is larger than the sum of its proper divisors (63108751).

820413581 is a wasteful number, since it uses less digits than its factorization.

820413581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63108750.

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 820413581 is about 28642.8626537223. The cubic root of 820413581 is about 936.1474967385.

The spelling of 820413581 in words is "eight hundred twenty million, four hundred thirteen thousand, five hundred eighty-one".