11961809 has 4 divisors (see below), whose sum is σ = 11988900. Its totient is φ = 11934720.

The previous prime is 11961797. The next prime is 11961821. The reversal of 11961809 is 90816911.

11961809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is an interprime number because it is at equal distance from previous prime (11961797) and next prime (11961821).

It can be written as a sum of positive squares in 2 ways, for example, as 3534400 + 8427409 = 1880^2 + 2903^2 .

It is a cyclic number.

It is not a de Polignac number, because 11961809 - 2¹² = 11957713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11961839) 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, 12872 + ... + 13769.

It is an arithmetic number, because the mean of its divisors is an integer number (2997225).

Almost surely, 2^11961809 is an apocalyptic number.

It is an amenable number.

11961809 is a deficient number, since it is larger than the sum of its proper divisors (27091).

11961809 is an equidigital number, since it uses as much as digits as its factorization.

11961809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27090.

The product of its (nonzero) digits is 3888, while the sum is 35.

The square root of 11961809 is about 3458.5848261970. The cubic root of 11961809 is about 228.6997138312.

The spelling of 11961809 in words is "eleven million, nine hundred sixty-one thousand, eight hundred nine".