13639670521 has 3 divisors (see below), whose sum is σ = 13639787311. Its totient is φ = 13639553732.

The previous prime is 13639670507. The next prime is 13639670549. The reversal of 13639670521 is 12507693631.

The square root of 13639670521 is 116789.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12507693631 = 107 ⋅116894333.

It can be written as a sum of positive squares in only one way, i.e., 67420521 + 13572250000 = 8211^2 + 116500^2 .

It is not a de Polignac number, because 13639670521 - 2¹¹ = 13639668473 is a prime.

It is a super-4 number, since 4×13639670521⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13639670621) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 58395 + ... + 175183.

Almost surely, 2^13639670521 is an apocalyptic number.

13639670521 is the 116789-th square number.

13639670521 is the 58395-th centered octagonal number.

It is an amenable number.

13639670521 is a deficient number, since it is larger than the sum of its proper divisors (116790).

13639670521 is an frugal number, since it uses more digits than its factorization.

13639670521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233578 (or 116789 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 43.

The spelling of 13639670521 in words is "thirteen billion, six hundred thirty-nine million, six hundred seventy thousand, five hundred twenty-one".