11811721 has 2 divisors, whose sum is σ = 11811722. Its totient is φ = 11811720.

The previous prime is 11811703. The next prime is 11811763. The reversal of 11811721 is 12711811.

11811721 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 weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11806096 + 5625 = 3436^2 + 75^2 .

It is a cyclic number.

It is not a de Polignac number, because 11811721 - 2¹¹ = 11809673 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 11811692 and 11811701.

It is not a weakly prime, because it can be changed into another prime (11811221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5905860 + 5905861.

It is an arithmetic number, because the mean of its divisors is an integer number (5905861).

Almost surely, 2^11811721 is an apocalyptic number.

It is an amenable number.

11811721 is a deficient number, since it is larger than the sum of its proper divisors (1).

11811721 is an equidigital number, since it uses as much as digits as its factorization.

11811721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 112, while the sum is 22.

The square root of 11811721 is about 3436.8184415241. The cubic root of 11811721 is about 227.7391664255.

The spelling of 11811721 in words is "eleven million, eight hundred eleven thousand, seven hundred twenty-one".