816316661 has 2 divisors, whose sum is σ = 816316662. Its totient is φ = 816316660.

The previous prime is 816316651. The next prime is 816316729. The reversal of 816316661 is 166613618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 458388100 + 357928561 = 21410^2 + 18919^2 .

It is a cyclic number.

It is not a de Polignac number, because 816316661 - 2⁶ = 816316597 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (816316651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408158330 + 408158331.

It is an arithmetic number, because the mean of its divisors is an integer number (408158331).

Almost surely, 2^816316661 is an apocalyptic number.

It is an amenable number.

816316661 is a deficient number, since it is larger than the sum of its proper divisors (1).

816316661 is an equidigital number, since it uses as much as digits as its factorization.

816316661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 38.

The square root of 816316661 is about 28571.2558526922. The cubic root of 816316661 is about 934.5866078395.

The spelling of 816316661 in words is "eight hundred sixteen million, three hundred sixteen thousand, six hundred sixty-one".