209842257 has 8 divisors (see below), whose sum is σ = 284376640. Its totient is φ = 137601360.

The previous prime is 209842229. The next prime is 209842267. The reversal of 209842257 is 752248902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 209842257 - 2⁸ = 209842001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209842267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 573157 + ... + 573522.

It is an arithmetic number, because the mean of its divisors is an integer number (35547080).

Almost surely, 2^209842257 is an apocalyptic number.

It is an amenable number.

209842257 is a deficient number, since it is larger than the sum of its proper divisors (74534383).

209842257 is a wasteful number, since it uses less digits than its factorization.

209842257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1146743.

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 209842257 is about 14485.9330731576. The cubic root of 209842257 is about 594.2433306821.

The spelling of 209842257 in words is "two hundred nine million, eight hundred forty-two thousand, two hundred fifty-seven".