820649 has 2 divisors, whose sum is σ = 820650. Its totient is φ = 820648.

The previous prime is 820643. The next prime is 820657. The reversal of 820649 is 946028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 577600 + 243049 = 760^2 + 493^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-820649 is a prime.

It is a Chen prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (820643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410324 + 410325.

It is an arithmetic number, because the mean of its divisors is an integer number (410325).

2⁸²⁰⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

820649 is a deficient number, since it is larger than the sum of its proper divisors (1).

820649 is an equidigital number, since it uses as much as digits as its factorization.

820649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 820649 is about 905.8967932386. The cubic root of 820649 is about 93.6237031186.

The spelling of 820649 in words is "eight hundred twenty thousand, six hundred forty-nine".