28438921 has 8 divisors (see below), whose sum is σ = 32750784. Its totient is φ = 24189360.

The previous prime is 28438897. The next prime is 28438987. The reversal of 28438921 is 12983482.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28438921 - 2⁵ = 28438889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28438321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14590 + ... + 16423.

It is an arithmetic number, because the mean of its divisors is an integer number (4093848).

Almost surely, 2^28438921 is an apocalyptic number.

It is an amenable number.

28438921 is a deficient number, since it is larger than the sum of its proper divisors (4311863).

28438921 is a wasteful number, since it uses less digits than its factorization.

28438921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31151.

The product of its digits is 27648, while the sum is 37.

The square root of 28438921 is about 5332.8154852760. The cubic root of 28438921 is about 305.2373714262.

The spelling of 28438921 in words is "twenty-eight million, four hundred thirty-eight thousand, nine hundred twenty-one".