1001105721 has 108 divisors (see below), whose sum is σ = 1881573876. Its totient is φ = 510935040.

The previous prime is 1001105701. The next prime is 1001105737. The reversal of 1001105721 is 1275011001.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 833765625 + 167340096 = 28875^2 + 12936^2 .

It is not a de Polignac number, because 1001105721 - 2⁶ = 1001105657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1001105694 and 1001105703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001105701) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 3895225 + ... + 3895481.

Almost surely, 2^1001105721 is an apocalyptic number.

1001105721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1001105721 is a deficient number, since it is larger than the sum of its proper divisors (880468155).

1001105721 is a wasteful number, since it uses less digits than its factorization.

1001105721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372 (or 351 counting only the distinct ones).

The product of its (nonzero) digits is 70, while the sum is 18.

The square root of 1001105721 is about 31640.2547556116. The cubic root of 1001105721 is about 1000.3684379035.

Adding to 1001105721 its reverse (1275011001), we get a palindrome (2276116722).

The spelling of 1001105721 in words is "one billion, one million, one hundred five thousand, seven hundred twenty-one".