209461691 has 2 divisors, whose sum is σ = 209461692. Its totient is φ = 209461690.

The previous prime is 209461687. The next prime is 209461711. The reversal of 209461691 is 196164902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 209461691 - 2² = 209461687 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (209461991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104730845 + 104730846.

It is an arithmetic number, because the mean of its divisors is an integer number (104730846).

Almost surely, 2^209461691 is an apocalyptic number.

209461691 is a deficient number, since it is larger than the sum of its proper divisors (1).

209461691 is an equidigital number, since it uses as much as digits as its factorization.

209461691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 209461691 is about 14472.7914031814. The cubic root of 209461691 is about 593.8838770913.

The spelling of 209461691 in words is "two hundred nine million, four hundred sixty-one thousand, six hundred ninety-one".