209899397 has 2 divisors, whose sum is σ = 209899398. Its totient is φ = 209899396.

The previous prime is 209899387. The next prime is 209899399. The reversal of 209899397 is 793998902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 202749121 + 7150276 = 14239^2 + 2674^2 .

It is a cyclic number.

It is not a de Polignac number, because 209899397 - 2⁴ = 209899381 is a prime.

Together with 209899399, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209899399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104949698 + 104949699.

It is an arithmetic number, because the mean of its divisors is an integer number (104949699).

Almost surely, 2^209899397 is an apocalyptic number.

It is an amenable number.

209899397 is a deficient number, since it is larger than the sum of its proper divisors (1).

209899397 is an equidigital number, since it uses as much as digits as its factorization.

209899397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2204496, while the sum is 56.

The square root of 209899397 is about 14487.9051970946. The cubic root of 209899397 is about 594.2972632295.

The spelling of 209899397 in words is "two hundred nine million, eight hundred ninety-nine thousand, three hundred ninety-seven".