821645449 has 2 divisors, whose sum is σ = 821645450. Its totient is φ = 821645448.

The previous prime is 821645431. The next prime is 821645477. The reversal of 821645449 is 944546128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 744907849 + 76737600 = 27293^2 + 8760^2 .

It is a cyclic number.

It is not a de Polignac number, because 821645449 - 2¹¹ = 821643401 is a prime.

It is not a weakly prime, because it can be changed into another prime (821645549) 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, 410822724 + 410822725.

It is an arithmetic number, because the mean of its divisors is an integer number (410822725).

Almost surely, 2^821645449 is an apocalyptic number.

It is an amenable number.

821645449 is a deficient number, since it is larger than the sum of its proper divisors (1).

821645449 is an equidigital number, since it uses as much as digits as its factorization.

821645449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 276480, while the sum is 43.

The square root of 821645449 is about 28664.3585136664. The cubic root of 821645449 is about 936.6158107136.

The spelling of 821645449 in words is "eight hundred twenty-one million, six hundred forty-five thousand, four hundred forty-nine".