8491409 has 2 divisors, whose sum is σ = 8491410. Its totient is φ = 8491408.

The previous prime is 8491391. The next prime is 8491411. The reversal of 8491409 is 9041948.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4774225 + 3717184 = 2185^2 + 1928^2 .

It is a cyclic number.

It is not a de Polignac number, because 8491409 - 2¹² = 8487313 is a prime.

Together with 8491411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (8491429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4245704 + 4245705.

It is an arithmetic number, because the mean of its divisors is an integer number (4245705).

Almost surely, 2^8491409 is an apocalyptic number.

It is an amenable number.

8491409 is a deficient number, since it is larger than the sum of its proper divisors (1).

8491409 is an equidigital number, since it uses as much as digits as its factorization.

8491409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 8491409 is about 2914.0022306100. The cubic root of 8491409 is about 204.0139760385.

The spelling of 8491409 in words is "eight million, four hundred ninety-one thousand, four hundred nine".