28991745 has 12 divisors (see below), whose sum is σ = 50252436. Its totient is φ = 15462240.

The previous prime is 28991737. The next prime is 28991791. The reversal of 28991745 is 54719982.

It can be written as a sum of positive squares in 2 ways, for example, as 15397776 + 13593969 = 3924^2 + 3687^2 .

It is not a de Polignac number, because 28991745 - 2³ = 28991737 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 644261 = 28991745 / (2 + 8 + 9 + 9 + 1 + 7 + 4 + 5).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 28991745.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 322086 + ... + 322175.

It is an arithmetic number, because the mean of its divisors is an integer number (4187703).

Almost surely, 2^28991745 is an apocalyptic number.

It is an amenable number.

28991745 is a deficient number, since it is larger than the sum of its proper divisors (21260691).

28991745 is a wasteful number, since it uses less digits than its factorization.

28991745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644272 (or 644269 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 28991745 is about 5384.3982950744. The cubic root of 28991745 is about 307.2025281062.

The spelling of 28991745 in words is "twenty-eight million, nine hundred ninety-one thousand, seven hundred forty-five".