28639575 has 30 divisors (see below), whose sum is σ = 53054144. Its totient is φ = 15273360.

The previous prime is 28639571. The next prime is 28639601. The reversal of 28639575 is 57593682.

It is a happy number.

28639575 is a `hidden beast` number, since 2 + 8 + 639 + 5 + 7 + 5 = 666.

It is not a de Polignac number, because 28639575 - 2² = 28639571 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28639575.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28639571) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 5047 + ... + 9096.

Almost surely, 2^28639575 is an apocalyptic number.

28639575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

28639575 is a deficient number, since it is larger than the sum of its proper divisors (24414569).

28639575 is a wasteful number, since it uses less digits than its factorization.

28639575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14165 (or 14151 counting only the distinct ones).

The product of its digits is 453600, while the sum is 45.

The square root of 28639575 is about 5351.5955564672. The cubic root of 28639575 is about 305.9535685029.

The spelling of 28639575 in words is "twenty-eight million, six hundred thirty-nine thousand, five hundred seventy-five".