1001805 has 48 divisors (see below), whose sum is σ = 1969920. Its totient is φ = 432768.

The previous prime is 1001801. The next prime is 1001807. The reversal of 1001805 is 5081001.

1001805 = 312² + 313² + ... + 321².

It is a happy number.

It is not a de Polignac number, because 1001805 - 2² = 1001801 is a prime.

It is a super-2 number, since 2×1001805² = 2007226516050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001801) 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 47 ways as a sum of consecutive naturals, for example, 21292 + ... + 21338.

It is an arithmetic number, because the mean of its divisors is an integer number (41040).

2^1001805 is an apocalyptic number.

1001805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1001805 is a deficient number, since it is larger than the sum of its proper divisors (968115).

1001805 is a wasteful number, since it uses less digits than its factorization.

1001805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98 (or 91 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 15.

The square root of 1001805 is about 1000.9020931140. The cubic root of 1001805 is about 100.0601305026.

Adding to 1001805 its sum of digits (15), we get a triangular number (1001820 = T₁₄₁₅).

Adding to 1001805 its reverse (5081001), we get a palindrome (6082806).

The spelling of 1001805 in words is "one million, one thousand, eight hundred five".