991625 has 8 divisors (see below), whose sum is σ = 1237704. Its totient is φ = 793200.

The previous prime is 991621. The next prime is 991633. The reversal of 991625 is 526199.

Added to its reverse (526199) it gives a square (1517824 = 1232²).

It can be written as a sum of positive squares in 4 ways, for example, as 100489 + 891136 = 317^2 + 944^2 .

It is not a de Polignac number, because 991625 - 2² = 991621 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991591 and 991600.

It is not an unprimeable number, because it can be changed into a prime (991621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3842 + ... + 4091.

It is an arithmetic number, because the mean of its divisors is an integer number (154713).

2⁹⁹¹⁶²⁵ is an apocalyptic number.

It is an amenable number.

991625 is a deficient number, since it is larger than the sum of its proper divisors (246079).

991625 is an equidigital number, since it uses as much as digits as its factorization.

991625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7948 (or 7938 counting only the distinct ones).

The product of its digits is 4860, while the sum is 32.

The square root of 991625 is about 995.8036955143. The cubic root of 991625 is about 99.7200503466.

Adding to 991625 its reverse (526199), we get a square (1517824 = 1232²).

The spelling of 991625 in words is "nine hundred ninety-one thousand, six hundred twenty-five".