816629981 has 2 divisors, whose sum is σ = 816629982. Its totient is φ = 816629980.

The previous prime is 816629977. The next prime is 816630043. The reversal of 816629981 is 189926618.

It is a happy number.

816629981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 798062500 + 18567481 = 28250^2 + 4309^2 .

It is a cyclic number.

It is not a de Polignac number, because 816629981 - 2² = 816629977 is a prime.

It is a super-3 number, since 3×816629981³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (816629911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408314990 + 408314991.

It is an arithmetic number, because the mean of its divisors is an integer number (408314991).

Almost surely, 2^816629981 is an apocalyptic number.

It is an amenable number.

816629981 is a deficient number, since it is larger than the sum of its proper divisors (1).

816629981 is an equidigital number, since it uses as much as digits as its factorization.

816629981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 373248, while the sum is 50.

The square root of 816629981 is about 28576.7384598033. The cubic root of 816629981 is about 934.7061640664.

The spelling of 816629981 in words is "eight hundred sixteen million, six hundred twenty-nine thousand, nine hundred eighty-one".