1001603 has 4 divisors (see below), whose sum is σ = 1003608. Its totient is φ = 999600.

The previous prime is 1001593. The next prime is 1001621. The reversal of 1001603 is 3061001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3061001 = 23 ⋅133087.

It is a cyclic number.

It is not a de Polignac number, because 1001603 - 2⁴ = 1001587 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1001683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 428 + ... + 1478.

It is an arithmetic number, because the mean of its divisors is an integer number (250902).

2^1001603 is an apocalyptic number.

1001603 is a deficient number, since it is larger than the sum of its proper divisors (2005).

1001603 is an equidigital number, since it uses as much as digits as its factorization.

1001603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2004.

The product of its (nonzero) digits is 18, while the sum is 11.

The square root of 1001603 is about 1000.8011790561. The cubic root of 1001603 is about 100.0534048075.

Adding to 1001603 its reverse (3061001), we get a palindrome (4062604).

The spelling of 1001603 in words is "one million, one thousand, six hundred three".