1000638 has 24 divisors (see below), whose sum is σ = 2263248. Its totient is φ = 318912.

The previous prime is 1000621. The next prime is 1000639. The reversal of 1000638 is 8360001.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a self number, because there is not a number n which added to its sum of digits gives 1000638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1000639) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 795 + ... + 1622.

It is an arithmetic number, because the mean of its divisors is an integer number (94302).

2^1000638 is an apocalyptic number.

1000638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1000638 is an abundant number, since it is smaller than the sum of its proper divisors (1262610).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1000638 is a wasteful number, since it uses less digits than its factorization.

1000638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2448 (or 2445 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1000638 is about 1000.3189491357. The cubic root of 1000638 is about 100.0212621456.

Adding to 1000638 its reverse (8360001), we get a palindrome (9360639).

The spelling of 1000638 in words is "one million, six hundred thirty-eight", and thus it is an aban number.