13247737721 has 4 divisors (see below), whose sum is σ = 13364974452. Its totient is φ = 13130500992.

The previous prime is 13247737697. The next prime is 13247737729. The reversal of 13247737721 is 12773774231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12773774231 = 43 ⋅297064517.

It can be written as a sum of positive squares in 2 ways, for example, as 332551696 + 12915186025 = 18236^2 + 113645^2 .

It is a cyclic number.

It is not a de Polignac number, because 13247737721 - 2¹⁴ = 13247721337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13247737729) 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, 58618196 + ... + 58618421.

It is an arithmetic number, because the mean of its divisors is an integer number (3341243613).

Almost surely, 2^13247737721 is an apocalyptic number.

It is an amenable number.

13247737721 is a deficient number, since it is larger than the sum of its proper divisors (117236731).

13247737721 is a wasteful number, since it uses less digits than its factorization.

13247737721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117236730.

The product of its digits is 345744, while the sum is 44.

The spelling of 13247737721 in words is "thirteen billion, two hundred forty-seven million, seven hundred thirty-seven thousand, seven hundred twenty-one".