11721809 has 8 divisors (see below), whose sum is σ = 12836928. Its totient is φ = 10614960.

The previous prime is 11721799. The next prime is 11721811. The reversal of 11721809 is 90812711.

11721809 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 11721809 - 2⁴ = 11721793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11721839) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1124 + ... + 4970.

It is an arithmetic number, because the mean of its divisors is an integer number (1604616).

Almost surely, 2^11721809 is an apocalyptic number.

It is an amenable number.

11721809 is a deficient number, since it is larger than the sum of its proper divisors (1115119).

11721809 is a wasteful number, since it uses less digits than its factorization.

11721809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4135.

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

The square root of 11721809 is about 3423.7127508014. The cubic root of 11721809 is about 227.1598361958.

The spelling of 11721809 in words is "eleven million, seven hundred twenty-one thousand, eight hundred nine".