28291921 has 8 divisors (see below), whose sum is σ = 32567360. Its totient is φ = 24074928.

The previous prime is 28291897. The next prime is 28291973. The reversal of 28291921 is 12919282.

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 28291921 - 2¹¹ = 28289873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28297921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13566 + ... + 15511.

It is an arithmetic number, because the mean of its divisors is an integer number (4070920).

Almost surely, 2^28291921 is an apocalyptic number.

It is an amenable number.

28291921 is a deficient number, since it is larger than the sum of its proper divisors (4275439).

28291921 is a wasteful number, since it uses less digits than its factorization.

28291921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29223.

The product of its digits is 5184, while the sum is 34.

The square root of 28291921 is about 5319.0150403999. The cubic root of 28291921 is about 304.7105414668.

The spelling of 28291921 in words is "twenty-eight million, two hundred ninety-one thousand, nine hundred twenty-one".