13638728 has 8 divisors (see below), whose sum is σ = 25572630. Its totient is φ = 6819360.

The previous prime is 13638707. The next prime is 13638739. The reversal of 13638728 is 82783631.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13410244 + 228484 = 3662^2 + 478^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 13638691 and 13638700.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 852413 + ... + 852428.

Almost surely, 2^13638728 is an apocalyptic number.

It is an amenable number.

13638728 is a deficient number, since it is larger than the sum of its proper divisors (11933902).

13638728 is a wasteful number, since it uses less digits than its factorization.

13638728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1704847 (or 1704843 counting only the distinct ones).

The product of its digits is 48384, while the sum is 38.

The square root of 13638728 is about 3693.0648518541. The cubic root of 13638728 is about 238.9229982503.

The spelling of 13638728 in words is "thirteen million, six hundred thirty-eight thousand, seven hundred twenty-eight".