13105081721 has 4 divisors (see below), whose sum is σ = 13105462692. Its totient is φ = 13104700752.

The previous prime is 13105081697. The next prime is 13105081753. The reversal of 13105081721 is 12718050131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12718050131 = 109 ⋅116679359.

It can be written as a sum of positive squares in 2 ways, for example, as 9552325696 + 3552756025 = 97736^2 + 59605^2 .

It is a cyclic number.

It is not a de Polignac number, because 13105081721 - 2¹⁰ = 13105080697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13105081021) 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, 133130 + ... + 209603.

It is an arithmetic number, because the mean of its divisors is an integer number (3276365673).

Almost surely, 2^13105081721 is an apocalyptic number.

It is an amenable number.

13105081721 is a deficient number, since it is larger than the sum of its proper divisors (380971).

13105081721 is an equidigital number, since it uses as much as digits as its factorization.

13105081721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 380970.

The product of its (nonzero) digits is 1680, while the sum is 29.

The spelling of 13105081721 in words is "thirteen billion, one hundred five million, eighty-one thousand, seven hundred twenty-one".