816571409 has 2 divisors, whose sum is σ = 816571410. Its totient is φ = 816571408.

The previous prime is 816571397. The next prime is 816571433. The reversal of 816571409 is 904175618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 462379009 + 354192400 = 21503^2 + 18820^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-816571409 is a prime.

It is not a weakly prime, because it can be changed into another prime (816571439) 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, 408285704 + 408285705.

It is an arithmetic number, because the mean of its divisors is an integer number (408285705).

Almost surely, 2^816571409 is an apocalyptic number.

It is an amenable number.

816571409 is a deficient number, since it is larger than the sum of its proper divisors (1).

816571409 is an equidigital number, since it uses as much as digits as its factorization.

816571409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 816571409 is about 28575.7136218853. The cubic root of 816571409 is about 934.6838165652.

The spelling of 816571409 in words is "eight hundred sixteen million, five hundred seventy-one thousand, four hundred nine".