209942749 has 4 divisors (see below), whose sum is σ = 214409664. Its totient is φ = 205475836.

The previous prime is 209942743. The next prime is 209942753. The reversal of 209942749 is 947249902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 209942749 - 2¹⁵ = 209909981 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 209942699 and 209942708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209942743) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2233387 + ... + 2233480.

It is an arithmetic number, because the mean of its divisors is an integer number (53602416).

Almost surely, 2^209942749 is an apocalyptic number.

It is an amenable number.

209942749 is a deficient number, since it is larger than the sum of its proper divisors (4466915).

209942749 is an equidigital number, since it uses as much as digits as its factorization.

209942749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4466914.

The product of its (nonzero) digits is 326592, while the sum is 46.

The square root of 209942749 is about 14489.4012643725. The cubic root of 209942749 is about 594.3381752121.

The spelling of 209942749 in words is "two hundred nine million, nine hundred forty-two thousand, seven hundred forty-nine".