409691 has 2 divisors, whose sum is σ = 409692. Its totient is φ = 409690.

The previous prime is 409657. The next prime is 409693. The reversal of 409691 is 196904.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 409691 - 2¹⁸ = 147547 is a prime.

Together with 409693, 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 (409693) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 204845 + 204846.

It is an arithmetic number, because the mean of its divisors is an integer number (204846).

2⁴⁰⁹⁶⁹¹ is an apocalyptic number.

409691 is a deficient number, since it is larger than the sum of its proper divisors (1).

409691 is an equidigital number, since it uses as much as digits as its factorization.

409691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 409691 is about 640.0710898018. The cubic root of 409691 is about 74.2709207298.

It can be divided in two parts, 40 and 9691, that multiplied together give a triangular number (387640 = T₈₈₀).

The spelling of 409691 in words is "four hundred nine thousand, six hundred ninety-one".