11211721 has 4 divisors (see below), whose sum is σ = 11871252. Its totient is φ = 10552192.

The previous prime is 11211689. The next prime is 11211749. The reversal of 11211721 is 12711211.

11211721 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 can be written as a sum of positive squares in 2 ways, for example, as 10465225 + 746496 = 3235^2 + 864^2 .

It is a cyclic number.

It is not a de Polignac number, because 11211721 - 2⁵ = 11211689 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11211695 and 11211704.

It is not an unprimeable number, because it can be changed into a prime (11211751) 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, 329740 + ... + 329773.

It is an arithmetic number, because the mean of its divisors is an integer number (2967813).

Almost surely, 2^11211721 is an apocalyptic number.

It is an amenable number.

11211721 is a deficient number, since it is larger than the sum of its proper divisors (659531).

11211721 is an equidigital number, since it uses as much as digits as its factorization.

11211721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 659530.

The product of its digits is 28, while the sum is 16.

The square root of 11211721 is about 3348.3908075373. The cubic root of 11211721 is about 223.8158097360.

Adding to 11211721 its reverse (12711211), we get a palindrome (23922932).

The spelling of 11211721 in words is "eleven million, two hundred eleven thousand, seven hundred twenty-one".