990881909 has 2 divisors, whose sum is σ = 990881910. Its totient is φ = 990881908.

The previous prime is 990881851. The next prime is 990881917. The reversal of 990881909 is 909188099.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 495952900 + 494929009 = 22270^2 + 22247^2 .

It is a cyclic number.

It is not a de Polignac number, because 990881909 - 2¹² = 990877813 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 (990881959) 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, 495440954 + 495440955.

It is an arithmetic number, because the mean of its divisors is an integer number (495440955).

Almost surely, 2^990881909 is an apocalyptic number.

It is an amenable number.

990881909 is a deficient number, since it is larger than the sum of its proper divisors (1).

990881909 is an equidigital number, since it uses as much as digits as its factorization.

990881909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 419904, while the sum is 53.

The square root of 990881909 is about 31478.2767793918. The cubic root of 990881909 is about 996.9513515208.

The spelling of 990881909 in words is "nine hundred ninety million, eight hundred eighty-one thousand, nine hundred nine".