28690138 has 4 divisors (see below), whose sum is σ = 43035210. Its totient is φ = 14345068.

The previous prime is 28690121. The next prime is 28690139. The reversal of 28690138 is 83109682.

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

It can be written as a sum of positive squares in only one way, i.e., 17581249 + 11108889 = 4193^2 + 3333^2 .

It is a junction number, because it is equal to n+sod(n) for n = 28690097 and 28690106.

It is not an unprimeable number, because it can be changed into a prime (28690139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7172533 + ... + 7172536.

Almost surely, 2^28690138 is an apocalyptic number.

28690138 is a deficient number, since it is larger than the sum of its proper divisors (14345072).

28690138 is a wasteful number, since it uses less digits than its factorization.

28690138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14345071.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 28690138 is about 5356.3175783368. The cubic root of 28690138 is about 306.1335157167.

The spelling of 28690138 in words is "twenty-eight million, six hundred ninety thousand, one hundred thirty-eight".