28400505 has 32 divisors (see below), whose sum is σ = 52233984. Its totient is φ = 12907776.

The previous prime is 28400503. The next prime is 28400507. The reversal of 28400505 is 50500482.

It is an interprime number because it is at equal distance from previous prime (28400503) and next prime (28400507).

It is not a de Polignac number, because 28400505 - 2¹ = 28400503 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28400503) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19999 + ... + 21371.

It is an arithmetic number, because the mean of its divisors is an integer number (1632312).

Almost surely, 2^28400505 is an apocalyptic number.

It is an amenable number.

28400505 is a deficient number, since it is larger than the sum of its proper divisors (23833479).

28400505 is a wasteful number, since it uses less digits than its factorization.

28400505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1585.

The product of its (nonzero) digits is 1600, while the sum is 24.

The square root of 28400505 is about 5329.2124183598. The cubic root of 28400505 is about 305.0998687557.

Adding to 28400505 its reverse (50500482), we get a palindrome (78900987).

The spelling of 28400505 in words is "twenty-eight million, four hundred thousand, five hundred five".