1990565 has 4 divisors (see below), whose sum is σ = 2388684. Its totient is φ = 1592448.

The previous prime is 1990559. The next prime is 1990577. The reversal of 1990565 is 5650991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5650991 = 107 ⋅52813.

It can be written as a sum of positive squares in 2 ways, for example, as 1214404 + 776161 = 1102^2 + 881^2 .

It is a cyclic number.

It is not a de Polignac number, because 1990565 - 2²⁰ = 941989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 199052 + ... + 199061.

It is an arithmetic number, because the mean of its divisors is an integer number (597171).

2^1990565 is an apocalyptic number.

It is an amenable number.

1990565 is a deficient number, since it is larger than the sum of its proper divisors (398119).

1990565 is an equidigital number, since it uses as much as digits as its factorization.

1990565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398118.

The product of its (nonzero) digits is 12150, while the sum is 35.

The square root of 1990565 is about 1410.8738426947. The cubic root of 1990565 is about 125.7936700375.

The spelling of 1990565 in words is "one million, nine hundred ninety thousand, five hundred sixty-five".