30728513 has 4 divisors (see below), whose sum is σ = 30743748. Its totient is φ = 30713280.

The previous prime is 30728497. The next prime is 30728521. The reversal of 30728513 is 31582703.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31582703 = 23 ⋅1373161.

It can be written as a sum of positive squares in 2 ways, for example, as 5798464 + 24930049 = 2408^2 + 4993^2 .

It is a cyclic number.

It is not a de Polignac number, because 30728513 - 2⁴ = 30728497 is a prime.

It is a super-2 number, since 2×30728513² = 1888483022382338, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (30728573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4028 + ... + 8813.

It is an arithmetic number, because the mean of its divisors is an integer number (7685937).

Almost surely, 2^30728513 is an apocalyptic number.

It is an amenable number.

30728513 is a deficient number, since it is larger than the sum of its proper divisors (15235).

30728513 is a wasteful number, since it uses less digits than its factorization.

30728513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15234.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 30728513 is about 5543.3304970929. The cubic root of 30728513 is about 313.2183385419.

The spelling of 30728513 in words is "thirty million, seven hundred twenty-eight thousand, five hundred thirteen".