820894409 has 2 divisors, whose sum is σ = 820894410. Its totient is φ = 820894408.

The previous prime is 820894391. The next prime is 820894423. The reversal of 820894409 is 904498028.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 820249600 + 644809 = 28640^2 + 803^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-820894409 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 820894409.

It is not a weakly prime, because it can be changed into another prime (820894429) 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, 410447204 + 410447205.

It is an arithmetic number, because the mean of its divisors is an integer number (410447205).

Almost surely, 2^820894409 is an apocalyptic number.

It is an amenable number.

820894409 is a deficient number, since it is larger than the sum of its proper divisors (1).

820894409 is an equidigital number, since it uses as much as digits as its factorization.

820894409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 165888, while the sum is 44.

The square root of 820894409 is about 28651.2549288858. The cubic root of 820894409 is about 936.3303467998.

The spelling of 820894409 in words is "eight hundred twenty million, eight hundred ninety-four thousand, four hundred nine".