28478731 has 4 divisors (see below), whose sum is σ = 28553472. Its totient is φ = 28403992.

The previous prime is 28478719. The next prime is 28478743. The reversal of 28478731 is 13787482.

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

It is an interprime number because it is at equal distance from previous prime (28478719) and next prime (28478743).

It is a cyclic number.

It is not a de Polignac number, because 28478731 - 2⁵ = 28478699 is a prime.

It is a super-2 number, since 2×28478731² = 1622076238740722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28478431) 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, 36796 + ... + 37561.

It is an arithmetic number, because the mean of its divisors is an integer number (7138368).

Almost surely, 2^28478731 is an apocalyptic number.

28478731 is a deficient number, since it is larger than the sum of its proper divisors (74741).

28478731 is an equidigital number, since it uses as much as digits as its factorization.

28478731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74740.

The product of its digits is 75264, while the sum is 40.

The square root of 28478731 is about 5336.5467298619. The cubic root of 28478731 is about 305.3797330639.

The spelling of 28478731 in words is "twenty-eight million, four hundred seventy-eight thousand, seven hundred thirty-one".