90909209 has 2 divisors, whose sum is σ = 90909210. Its totient is φ = 90909208.

The previous prime is 90909199. The next prime is 90909223. The reversal of 90909209 is 90290909.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50013184 + 40896025 = 7072^2 + 6395^2 .

It is a cyclic number.

It is not a de Polignac number, because 90909209 - 2⁴ = 90909193 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (90909239) 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, 45454604 + 45454605.

It is an arithmetic number, because the mean of its divisors is an integer number (45454605).

Almost surely, 2^90909209 is an apocalyptic number.

It is an amenable number.

90909209 is a deficient number, since it is larger than the sum of its proper divisors (1).

90909209 is an equidigital number, since it uses as much as digits as its factorization.

90909209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13122, while the sum is 38.

The square root of 90909209 is about 9534.6320851934. The cubic root of 90909209 is about 449.6445077185.

It can be divided in two parts, 90909 and 209, that multiplied together give a palindrome (18999981).

The spelling of 90909209 in words is "ninety million, nine hundred nine thousand, two hundred nine".