820880509 has 2 divisors, whose sum is σ = 820880510. Its totient is φ = 820880508.

The previous prime is 820880497. The next prime is 820880561. The reversal of 820880509 is 905088028.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 762312100 + 58568409 = 27610^2 + 7653^2 .

It is a cyclic number.

It is not a de Polignac number, because 820880509 - 2⁷ = 820880381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820880569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410440254 + 410440255.

It is an arithmetic number, because the mean of its divisors is an integer number (410440255).

Almost surely, 2^820880509 is an apocalyptic number.

It is an amenable number.

820880509 is a deficient number, since it is larger than the sum of its proper divisors (1).

820880509 is an equidigital number, since it uses as much as digits as its factorization.

820880509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46080, while the sum is 40.

The square root of 820880509 is about 28651.0123555870. The cubic root of 820880509 is about 936.3250618873.

The spelling of 820880509 in words is "eight hundred twenty million, eight hundred eighty thousand, five hundred nine".