11391721 has 8 divisors (see below), whose sum is σ = 12585600. Its totient is φ = 10224240.

The previous prime is 11391707. The next prime is 11391749. The reversal of 11391721 is 12719311.

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 11391721 - 2⁷ = 11391593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11391791) 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, 5686 + ... + 7423.

It is an arithmetic number, because the mean of its divisors is an integer number (1573200).

Almost surely, 2^11391721 is an apocalyptic number.

11391721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11391721 is a deficient number, since it is larger than the sum of its proper divisors (1193879).

11391721 is a wasteful number, since it uses less digits than its factorization.

11391721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13199.

The product of its digits is 378, while the sum is 25.

The square root of 11391721 is about 3375.1623664648. The cubic root of 11391721 is about 225.0072162295.

The spelling of 11391721 in words is "eleven million, three hundred ninety-one thousand, seven hundred twenty-one".