11821709 has 4 divisors (see below), whose sum is σ = 11833116. Its totient is φ = 11810304.

The previous prime is 11821699. The next prime is 11821717. The reversal of 11821709 is 90712811.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90712811 = 7 ⋅12958973.

It can be written as a sum of positive squares in 2 ways, for example, as 5175625 + 6646084 = 2275^2 + 2578^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11821709 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11821729) 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 3 ways as a sum of consecutive naturals, for example, 3974 + ... + 6279.

It is an arithmetic number, because the mean of its divisors is an integer number (2958279).

Almost surely, 2^11821709 is an apocalyptic number.

It is an amenable number.

11821709 is a deficient number, since it is larger than the sum of its proper divisors (11407).

11821709 is a wasteful number, since it uses less digits than its factorization.

11821709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11406.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 11821709 is about 3438.2712225768. The cubic root of 11821709 is about 227.8033404761.

The spelling of 11821709 in words is "eleven million, eight hundred twenty-one thousand, seven hundred nine".