28778505 has 16 divisors (see below), whose sum is σ = 52623744. Its totient is φ = 13155840.

The previous prime is 28778471. The next prime is 28778531. The reversal of 28778505 is 50587782.

It is a happy number.

It is not a de Polignac number, because 28778505 - 2⁶ = 28778441 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 136936 + ... + 137145.

It is an arithmetic number, because the mean of its divisors is an integer number (3288984).

Almost surely, 2^28778505 is an apocalyptic number.

It is an amenable number.

28778505 is a deficient number, since it is larger than the sum of its proper divisors (23845239).

28778505 is a wasteful number, since it uses less digits than its factorization.

28778505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274096.

The product of its (nonzero) digits is 156800, while the sum is 42.

The square root of 28778505 is about 5364.5600938008. The cubic root of 28778505 is about 306.4474955459.

The spelling of 28778505 in words is "twenty-eight million, seven hundred seventy-eight thousand, five hundred five".