28667821 has 16 divisors (see below), whose sum is σ = 36820224. Its totient is φ = 21694464.

The previous prime is 28667819. The next prime is 28667833. The reversal of 28667821 is 12876682.

It is a cyclic number.

It is not a de Polignac number, because 28667821 - 2¹ = 28667819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28667801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4756 + ... + 8941.

It is an arithmetic number, because the mean of its divisors is an integer number (2301264).

Almost surely, 2^28667821 is an apocalyptic number.

It is an amenable number.

28667821 is a deficient number, since it is larger than the sum of its proper divisors (8152403).

28667821 is a wasteful number, since it uses less digits than its factorization.

28667821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13740.

The product of its digits is 64512, while the sum is 40.

The square root of 28667821 is about 5354.2339321326. The cubic root of 28667821 is about 306.0541184701.

The spelling of 28667821 in words is "twenty-eight million, six hundred sixty-seven thousand, eight hundred twenty-one".