91989409 has 2 divisors, whose sum is σ = 91989410. Its totient is φ = 91989408.

The previous prime is 91989389. The next prime is 91989413. The reversal of 91989409 is 90498919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73153809 + 18835600 = 8553^2 + 4340^2 .

It is a cyclic number.

It is not a de Polignac number, because 91989409 - 2¹³ = 91981217 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91989109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45994704 + 45994705.

It is an arithmetic number, because the mean of its divisors is an integer number (45994705).

Almost surely, 2^91989409 is an apocalyptic number.

It is an amenable number.

91989409 is a deficient number, since it is larger than the sum of its proper divisors (1).

91989409 is an equidigital number, since it uses as much as digits as its factorization.

91989409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 209952, while the sum is 49.

The square root of 91989409 is about 9591.1109366955. The cubic root of 91989409 is about 451.4184198538.

The spelling of 91989409 in words is "ninety-one million, nine hundred eighty-nine thousand, four hundred nine".