28628939 has 4 divisors (see below), whose sum is σ = 28676256. Its totient is φ = 28581624.

The previous prime is 28628923. The next prime is 28628981. The reversal of 28628939 is 93982682.

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

It is a cyclic number.

It is not a de Polignac number, because 28628939 - 2⁴ = 28628923 is a prime.

It is a super-2 number, since 2×28628939² = 1639232296531442, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28628893 and 28628902.

It is not an unprimeable number, because it can be changed into a prime (28628909) 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, 22739 + ... + 23964.

It is an arithmetic number, because the mean of its divisors is an integer number (7169064).

Almost surely, 2^28628939 is an apocalyptic number.

28628939 is a deficient number, since it is larger than the sum of its proper divisors (47317).

28628939 is an equidigital number, since it uses as much as digits as its factorization.

28628939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47316.

The product of its digits is 373248, while the sum is 47.

The square root of 28628939 is about 5350.6017418604. The cubic root of 28628939 is about 305.9156893901.

The spelling of 28628939 in words is "twenty-eight million, six hundred twenty-eight thousand, nine hundred thirty-nine".