99840409 has 2 divisors, whose sum is σ = 99840410. Its totient is φ = 99840408.

The previous prime is 99840353. The next prime is 99840443. The reversal of 99840409 is 90404899.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 85377600 + 14462809 = 9240^2 + 3803^2 .

It is a cyclic number.

It is not a de Polignac number, because 99840409 - 2⁹ = 99839897 is a prime.

It is not a weakly prime, because it can be changed into another prime (99840479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49920204 + 49920205.

It is an arithmetic number, because the mean of its divisors is an integer number (49920205).

Almost surely, 2^99840409 is an apocalyptic number.

It is an amenable number.

99840409 is a deficient number, since it is larger than the sum of its proper divisors (1).

99840409 is an equidigital number, since it uses as much as digits as its factorization.

99840409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 99840409 is about 9992.0172637961. The cubic root of 99840409 is about 463.9118332902.

The spelling of 99840409 in words is "ninety-nine million, eight hundred forty thousand, four hundred nine".