991225321 has 4 divisors (see below), whose sum is σ = 991355472. Its totient is φ = 991095172.

The previous prime is 991225283. The next prime is 991225373. The reversal of 991225321 is 123522199.

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.

It is a cyclic number.

It is not a de Polignac number, because 991225321 - 2⁹ = 991224809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991225021) 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, 52891 + ... + 69136.

It is an arithmetic number, because the mean of its divisors is an integer number (247838868).

Almost surely, 2^991225321 is an apocalyptic number.

It is an amenable number.

991225321 is a deficient number, since it is larger than the sum of its proper divisors (130151).

991225321 is a wasteful number, since it uses less digits than its factorization.

991225321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130150.

The product of its digits is 9720, while the sum is 34.

The square root of 991225321 is about 31483.7310527199. The cubic root of 991225321 is about 997.0665100513.

The spelling of 991225321 in words is "nine hundred ninety-one million, two hundred twenty-five thousand, three hundred twenty-one".