28778749 has 4 divisors (see below), whose sum is σ = 30293440. Its totient is φ = 27264060.

The previous prime is 28778747. The next prime is 28778777. The reversal of 28778749 is 94787782.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28778749 - 2¹ = 28778747 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28778696 and 28778705.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28778747) 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, 757317 + ... + 757354.

It is an arithmetic number, because the mean of its divisors is an integer number (7573360).

Almost surely, 2^28778749 is an apocalyptic number.

It is an amenable number.

28778749 is a deficient number, since it is larger than the sum of its proper divisors (1514691).

28778749 is a wasteful number, since it uses less digits than its factorization.

28778749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1514690.

The product of its digits is 1580544, while the sum is 52.

The square root of 28778749 is about 5364.5828355987. The cubic root of 28778749 is about 306.4483616203.

The spelling of 28778749 in words is "twenty-eight million, seven hundred seventy-eight thousand, seven hundred forty-nine".