91138409 has 2 divisors, whose sum is σ = 91138410. Its totient is φ = 91138408.

The previous prime is 91138393. The next prime is 91138441. The reversal of 91138409 is 90483119.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 84584809 + 6553600 = 9197^2 + 2560^2 .

It is an emirp because it is prime and its reverse (90483119) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91138409 - 2⁴ = 91138393 is a prime.

It is not a weakly prime, because it can be changed into another prime (91138709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45569204 + 45569205.

It is an arithmetic number, because the mean of its divisors is an integer number (45569205).

Almost surely, 2^91138409 is an apocalyptic number.

It is an amenable number.

91138409 is a deficient number, since it is larger than the sum of its proper divisors (1).

91138409 is an equidigital number, since it uses as much as digits as its factorization.

91138409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 91138409 is about 9546.6438605407. The cubic root of 91138409 is about 450.0220713454.

The spelling of 91138409 in words is "ninety-one million, one hundred thirty-eight thousand, four hundred nine".