1981825 has 6 divisors (see below), whose sum is σ = 2457494. Its totient is φ = 1585440.

The previous prime is 1981813. The next prime is 1981853. The reversal of 1981825 is 5281891.

It can be written as a sum of positive squares in 3 ways, for example, as 10609 + 1971216 = 103^2 + 1404^2 .

It is not a de Polignac number, because 1981825 - 2¹³ = 1973633 is a prime.

It is a Duffinian number.

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 5 ways as a sum of consecutive naturals, for example, 39612 + ... + 39661.

2^1981825 is an apocalyptic number.

It is an amenable number.

1981825 is a deficient number, since it is larger than the sum of its proper divisors (475669).

1981825 is an equidigital number, since it uses as much as digits as its factorization.

1981825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79283 (or 79278 counting only the distinct ones).

The product of its digits is 5760, while the sum is 34.

The square root of 1981825 is about 1407.7730640980. The cubic root of 1981825 is about 125.6092919478.

The spelling of 1981825 in words is "one million, nine hundred eighty-one thousand, eight hundred twenty-five".