9991225 has 12 divisors (see below), whose sum is σ = 12817260. Its totient is φ = 7716800.

The previous prime is 9991211. The next prime is 9991259. The reversal of 9991225 is 5221999.

It can be written as a sum of positive squares in 6 ways, for example, as 87616 + 9903609 = 296^2 + 3147^2 .

It is not a de Polignac number, because 9991225 - 2¹³ = 9983033 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6166 + ... + 7615.

It is an arithmetic number, because the mean of its divisors is an integer number (1068105).

Almost surely, 2^9991225 is an apocalyptic number.

It is an amenable number.

9991225 is a deficient number, since it is larger than the sum of its proper divisors (2826035).

9991225 is a wasteful number, since it uses less digits than its factorization.

9991225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13820 (or 13815 counting only the distinct ones).

The product of its digits is 14580, while the sum is 37.

The square root of 9991225 is about 3160.8899063397. The cubic root of 9991225 is about 215.3804333470.

The spelling of 9991225 in words is "nine million, nine hundred ninety-one thousand, two hundred twenty-five".