804778561 has 2 divisors, whose sum is σ = 804778562. Its totient is φ = 804778560.

The previous prime is 804778547. The next prime is 804778567. The reversal of 804778561 is 165877408.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 642369025 + 162409536 = 25345^2 + 12744^2 .

It is a cyclic number.

It is not a de Polignac number, because 804778561 - 2¹⁵ = 804745793 is a prime.

It is not a weakly prime, because it can be changed into another prime (804778567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 402389280 + 402389281.

It is an arithmetic number, because the mean of its divisors is an integer number (402389281).

Almost surely, 2^804778561 is an apocalyptic number.

It is an amenable number.

804778561 is a deficient number, since it is larger than the sum of its proper divisors (1).

804778561 is an equidigital number, since it uses as much as digits as its factorization.

804778561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 376320, while the sum is 46.

The square root of 804778561 is about 28368.6193002056. The cubic root of 804778561 is about 930.1624416600.

The spelling of 804778561 in words is "eight hundred four million, seven hundred seventy-eight thousand, five hundred sixty-one".