11191312521 has 27 divisors (see below), whose sum is σ = 16338979111. Its totient is φ = 7381533264.

The previous prime is 11191312507. The next prime is 11191312537. The reversal of 11191312521 is 12521319111.

It is a happy number.

The square root of 11191312521 is 105789.

It is a perfect power (a square), and thus also a powerful number.

11191312521 is a `hidden beast` number, since 1 + 1 + 1 + 9 + 131 + 2 + 521 = 666.

It can be written as a sum of positive squares in only one way, i.e., 10965231225 + 226081296 = 104715^2 + 15036^2 .

It is not a de Polignac number, because 11191312521 - 2⁷ = 11191312393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11191312501) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 56808595 + ... + 56808791.

Almost surely, 2^11191312521 is an apocalyptic number.

11191312521 is the 105789-th square number.

11191312521 is the 52895-th centered octagonal number.

It is an amenable number.

11191312521 is a deficient number, since it is larger than the sum of its proper divisors (5147666590).

11191312521 is an frugal number, since it uses more digits than its factorization.

11191312521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758 (or 379 counting only the distinct ones).

The product of its digits is 540, while the sum is 27.

The spelling of 11191312521 in words is "eleven billion, one hundred ninety-one million, three hundred twelve thousand, five hundred twenty-one".