991225 has 12 divisors (see below), whose sum is σ = 1269760. Its totient is φ = 766800.

The previous prime is 991223. The next prime is 991229. The reversal of 991225 is 522199.

It is not a de Polignac number, because 991225 - 2¹ = 991223 is a prime.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 991193 and 991202.

It is not an unprimeable number, because it can be changed into a prime (991223) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 136 + ... + 1414.

2⁹⁹¹²²⁵ is an apocalyptic number.

It is an amenable number.

991225 is a deficient number, since it is larger than the sum of its proper divisors (278535).

991225 is a wasteful number, since it uses less digits than its factorization.

991225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1320 (or 1315 counting only the distinct ones).

The product of its digits is 1620, while the sum is 28.

The square root of 991225 is about 995.6028324588. The cubic root of 991225 is about 99.7066402421.

The spelling of 991225 in words is "nine hundred ninety-one thousand, two hundred twenty-five".