990688081 has 2 divisors, whose sum is σ = 990688082. Its totient is φ = 990688080.

The previous prime is 990688067. The next prime is 990688087. The reversal of 990688081 is 180886099.

It is a happy number.

990688081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 598291600 + 392396481 = 24460^2 + 19809^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-990688081 is a prime.

It is a super-2 number, since 2×990688081² = 1962925747670925122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (990688087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495344040 + 495344041.

It is an arithmetic number, because the mean of its divisors is an integer number (495344041).

Almost surely, 2^990688081 is an apocalyptic number.

It is an amenable number.

990688081 is a deficient number, since it is larger than the sum of its proper divisors (1).

990688081 is an equidigital number, since it uses as much as digits as its factorization.

990688081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 248832, while the sum is 49.

The square root of 990688081 is about 31475.1978707045. The cubic root of 990688081 is about 996.8863421973.

The spelling of 990688081 in words is "nine hundred ninety million, six hundred eighty-eight thousand, eighty-one".