13108721 has 4 divisors (see below), whose sum is σ = 13256100. Its totient is φ = 12961344.

The previous prime is 13108703. The next prime is 13108741. The reversal of 13108721 is 12780131.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4906225 + 8202496 = 2215^2 + 2864^2 .

It is a cyclic number.

It is not a de Polignac number, because 13108721 - 2⁶ = 13108657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13108741) 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, 73556 + ... + 73733.

It is an arithmetic number, because the mean of its divisors is an integer number (3314025).

Almost surely, 2^13108721 is an apocalyptic number.

It is an amenable number.

13108721 is a deficient number, since it is larger than the sum of its proper divisors (147379).

13108721 is an equidigital number, since it uses as much as digits as its factorization.

13108721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147378.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 13108721 is about 3620.5967740139. The cubic root of 13108721 is about 235.7871356968.

Adding to 13108721 its reverse (12780131), we get a palindrome (25888852).

The spelling of 13108721 in words is "thirteen million, one hundred eight thousand, seven hundred twenty-one".