2001565 has 4 divisors (see below), whose sum is σ = 2401884. Its totient is φ = 1601248.

The previous prime is 2001553. The next prime is 2001581. The reversal of 2001565 is 5651002.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1390041 + 611524 = 1179^2 + 782^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001565 - 2⁵ = 2001533 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, 200152 + ... + 200161.

It is an arithmetic number, because the mean of its divisors is an integer number (600471).

2^2001565 is an apocalyptic number.

It is an amenable number.

2001565 is a deficient number, since it is larger than the sum of its proper divisors (400319).

2001565 is an equidigital number, since it uses as much as digits as its factorization.

2001565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400318.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 2001565 is about 1414.7667652302. The cubic root of 2001565 is about 126.0249593622.

Adding to 2001565 its reverse (5651002), we get a palindrome (7652567).

The spelling of 2001565 in words is "two million, one thousand, five hundred sixty-five".