11905721 has 4 divisors (see below), whose sum is σ = 11913600. Its totient is φ = 11897844.

The previous prime is 11905717. The next prime is 11905727. The reversal of 11905721 is 12750911.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 11905721 - 2² = 11905717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11905727) 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, 881 + ... + 4958.

It is an arithmetic number, because the mean of its divisors is an integer number (2978400).

Almost surely, 2^11905721 is an apocalyptic number.

It is an amenable number.

11905721 is a deficient number, since it is larger than the sum of its proper divisors (7879).

11905721 is an equidigital number, since it uses as much as digits as its factorization.

11905721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7878.

The product of its (nonzero) digits is 630, while the sum is 26.

The square root of 11905721 is about 3450.4667800169. The cubic root of 11905721 is about 228.3417019091.

The spelling of 11905721 in words is "eleven million, nine hundred five thousand, seven hundred twenty-one".