209429491 has 2 divisors, whose sum is σ = 209429492. Its totient is φ = 209429490.

The previous prime is 209429461. The next prime is 209429497. The reversal of 209429491 is 194924902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209429491 - 2⁹ = 209428979 is a prime.

It is not a weakly prime, because it can be changed into another prime (209429497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104714745 + 104714746.

It is an arithmetic number, because the mean of its divisors is an integer number (104714746).

Almost surely, 2^209429491 is an apocalyptic number.

209429491 is a deficient number, since it is larger than the sum of its proper divisors (1).

209429491 is an equidigital number, since it uses as much as digits as its factorization.

209429491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 209429491 is about 14471.6789281686. The cubic root of 209429491 is about 593.8534434580.

The spelling of 209429491 in words is "two hundred nine million, four hundred twenty-nine thousand, four hundred ninety-one".