1991725 has 6 divisors (see below), whose sum is σ = 2469770. Its totient is φ = 1593360.

The previous prime is 1991723. The next prime is 1991729. The reversal of 1991725 is 5271991.

It can be written as a sum of positive squares in 3 ways, for example, as 133956 + 1857769 = 366^2 + 1363^2 .

It is not a de Polignac number, because 1991725 - 2¹ = 1991723 is a prime.

It is a super-3 number, since 3×1991725³ = 23703330861342609375, which contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991723) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 39810 + ... + 39859.

2^1991725 is an apocalyptic number.

It is an amenable number.

1991725 is a deficient number, since it is larger than the sum of its proper divisors (478045).

1991725 is an equidigital number, since it uses as much as digits as its factorization.

1991725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79679 (or 79674 counting only the distinct ones).

The product of its digits is 5670, while the sum is 34.

The square root of 1991725 is about 1411.2848755655. The cubic root of 1991725 is about 125.8181006760.

The spelling of 1991725 in words is "one million, nine hundred ninety-one thousand, seven hundred twenty-five".