28691257 has 16 divisors (see below), whose sum is σ = 34860672. Its totient is φ = 23051520.

The previous prime is 28691219. The next prime is 28691261. The reversal of 28691257 is 75219682.

It is a cyclic number.

It is not a de Polignac number, because 28691257 - 2¹¹ = 28689209 is a prime.

Its product of digits (60480) is a multiple of the sum of its prime divisors (1008).

It is not an unprimeable number, because it can be changed into a prime (28691207) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54598 + ... + 55120.

It is an arithmetic number, because the mean of its divisors is an integer number (2178792).

Almost surely, 2^28691257 is an apocalyptic number.

It is an amenable number.

28691257 is a deficient number, since it is larger than the sum of its proper divisors (6169415).

28691257 is a wasteful number, since it uses less digits than its factorization.

28691257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1008.

The product of its digits is 60480, while the sum is 40.

The square root of 28691257 is about 5356.4220334100. The cubic root of 28691257 is about 306.1374957016.

The spelling of 28691257 in words is "twenty-eight million, six hundred ninety-one thousand, two hundred fifty-seven".