11521721 has 8 divisors (see below), whose sum is σ = 12042624. Its totient is φ = 11012400.

The previous prime is 11521717. The next prime is 11521747. The reversal of 11521721 is 12712511.

It is a happy number.

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 11521721 - 2² = 11521717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 11521693 and 11521702.

It is not an unprimeable number, because it can be changed into a prime (11521711) 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, 830 + ... + 4871.

It is an arithmetic number, because the mean of its divisors is an integer number (1505328).

Almost surely, 2^11521721 is an apocalyptic number.

It is an amenable number.

11521721 is a deficient number, since it is larger than the sum of its proper divisors (520903).

11521721 is an equidigital number, since it uses as much as digits as its factorization.

11521721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5791.

The product of its digits is 140, while the sum is 20.

The square root of 11521721 is about 3394.3660674712. The cubic root of 11521721 is about 225.8598930590.

The spelling of 11521721 in words is "eleven million, five hundred twenty-one thousand, seven hundred twenty-one".