1001538 has 32 divisors (see below), whose sum is σ = 2358720. Its totient is φ = 313920.

The previous prime is 1001531. The next prime is 1001549. The reversal of 1001538 is 8351001.

It is a happy number.

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 1001538.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 373 + ... + 1463.

It is an arithmetic number, because the mean of its divisors is an integer number (73710).

2^1001538 is an apocalyptic number.

1001538 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1001538, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1179360).

1001538 is an abundant number, since it is smaller than the sum of its proper divisors (1357182).

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

1001538 is a wasteful number, since it uses less digits than its factorization.

1001538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1119 (or 1113 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 1001538 is about 1000.7687045467. The cubic root of 1001538 is about 100.0512404064.

Adding to 1001538 its reverse (8351001), we get a palindrome (9352539).

The spelling of 1001538 in words is "one million, one thousand, five hundred thirty-eight".