4991209 has 4 divisors (see below), whose sum is σ = 5047380. Its totient is φ = 4935040.

The previous prime is 4991201. The next prime is 4991237. The reversal of 4991209 is 9021994.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 685584 + 4305625 = 828^2 + 2075^2 .

It is a cyclic number.

It is not a de Polignac number, because 4991209 - 2³ = 4991201 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4991201) 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, 27952 + ... + 28129.

It is an arithmetic number, because the mean of its divisors is an integer number (1261845).

Almost surely, 2^4991209 is an apocalyptic number.

It is an amenable number.

4991209 is a deficient number, since it is larger than the sum of its proper divisors (56171).

4991209 is an equidigital number, since it uses as much as digits as its factorization.

4991209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56170.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 4991209 is about 2234.1013853449. The cubic root of 4991209 is about 170.8973198867.

The spelling of 4991209 in words is "four million, nine hundred ninety-one thousand, two hundred nine".