28640538 has 12 divisors (see below), whose sum is σ = 62054538. Its totient is φ = 9546840.

The previous prime is 28640527. The next prime is 28640551. The reversal of 28640538 is 83504682.

28640538 is a `hidden beast` number, since 2 + 8 + 640 + 5 + 3 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 27594009 + 1046529 = 5253^2 + 1023^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 795553 + ... + 795588.

Almost surely, 2^28640538 is an apocalyptic number.

28640538 is an abundant number, since it is smaller than the sum of its proper divisors (33414000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28640538 is a wasteful number, since it uses less digits than its factorization.

28640538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1591149 (or 1591146 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 28640538 is about 5351.6855288778. The cubic root of 28640538 is about 305.9569976737.

The spelling of 28640538 in words is "twenty-eight million, six hundred forty thousand, five hundred thirty-eight".