820642489 has 2 divisors, whose sum is σ = 820642490. Its totient is φ = 820642488.

The previous prime is 820642481. The next prime is 820642523. The reversal of 820642489 is 984246028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 615436864 + 205205625 = 24808^2 + 14325^2 .

It is a cyclic number.

It is not a de Polignac number, because 820642489 - 2³ = 820642481 is a prime.

It is not a weakly prime, because it can be changed into another prime (820642481) 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 as a sum of consecutive naturals, namely, 410321244 + 410321245.

It is an arithmetic number, because the mean of its divisors is an integer number (410321245).

Almost surely, 2^820642489 is an apocalyptic number.

It is an amenable number.

820642489 is a deficient number, since it is larger than the sum of its proper divisors (1).

820642489 is an equidigital number, since it uses as much as digits as its factorization.

820642489 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 221184, while the sum is 43.

The square root of 820642489 is about 28646.8582745124. The cubic root of 820642489 is about 936.2345551560.

The spelling of 820642489 in words is "eight hundred twenty million, six hundred forty-two thousand, four hundred eighty-nine".