10991231 has 4 divisors (see below), whose sum is σ = 11637792. Its totient is φ = 10344672.

The previous prime is 10991219. The next prime is 10991237. The reversal of 10991231 is 13219901.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-10991231 is a prime.

It is a super-2 number, since 2×10991231² = 241614317790722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 10991231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10991237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 323255 + ... + 323288.

It is an arithmetic number, because the mean of its divisors is an integer number (2909448).

Almost surely, 2^10991231 is an apocalyptic number.

10991231 is a deficient number, since it is larger than the sum of its proper divisors (646561).

10991231 is an equidigital number, since it uses as much as digits as its factorization.

10991231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646560.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 10991231 is about 3315.3025502961. The cubic root of 10991231 is about 222.3388961298.

The spelling of 10991231 in words is "ten million, nine hundred ninety-one thousand, two hundred thirty-one".