11111521 has 4 divisors (see below), whose sum is σ = 11191600. Its totient is φ = 11031444.

The previous prime is 11111509. The next prime is 11111531. The reversal of 11111521 is 12511111.

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 an emirpimes, since its reverse is a distinct semiprime: 12511111 = 67 ⋅186733.

It is a cyclic number.

It is not a de Polignac number, because 11111521 - 2⁷ = 11111393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11111531) 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, 39831 + ... + 40108.

It is an arithmetic number, because the mean of its divisors is an integer number (2797900).

Almost surely, 2^11111521 is an apocalyptic number.

It is an amenable number.

11111521 is a deficient number, since it is larger than the sum of its proper divisors (80079).

11111521 is an equidigital number, since it uses as much as digits as its factorization.

11111521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80078.

The product of its digits is 10, while the sum is 13.

The square root of 11111521 is about 3333.3948160996. The cubic root of 11111521 is about 223.1470605916.

Adding to 11111521 its reverse (12511111), we get a palindrome (23622632).

The spelling of 11111521 in words is "eleven million, one hundred eleven thousand, five hundred twenty-one".