28679921 has 8 divisors (see below), whose sum is σ = 29543784. Its totient is φ = 27820800.

The previous prime is 28679909. The next prime is 28679933. The reversal of 28679921 is 12997682.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28679909) and next prime (28679933).

It can be written as a sum of positive squares in 4 ways, for example, as 21715600 + 6964321 = 4660^2 + 2639^2 .

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 28679921 - 2⁶ = 28679857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28679621) 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, 13871 + ... + 15803.

It is an arithmetic number, because the mean of its divisors is an integer number (3692973).

Almost surely, 2^28679921 is an apocalyptic number.

It is an amenable number.

28679921 is a deficient number, since it is larger than the sum of its proper divisors (863863).

28679921 is a wasteful number, since it uses less digits than its factorization.

28679921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2371.

The product of its digits is 108864, while the sum is 44.

The square root of 28679921 is about 5355.3637598206. The cubic root of 28679921 is about 306.0971717822.

The spelling of 28679921 in words is "twenty-eight million, six hundred seventy-nine thousand, nine hundred twenty-one".