28098421 has 4 divisors (see below), whose sum is σ = 30259852. Its totient is φ = 25936992.

The previous prime is 28098409. The next prime is 28098481. The reversal of 28098421 is 12489082.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16443025 + 11655396 = 4055^2 + 3414^2 .

It is a cyclic number.

It is not a de Polignac number, because 28098421 - 2¹¹ = 28096373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28098481) 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 3 ways as a sum of consecutive naturals, for example, 1080696 + ... + 1080721.

It is an arithmetic number, because the mean of its divisors is an integer number (7564963).

Almost surely, 2^28098421 is an apocalyptic number.

It is an amenable number.

28098421 is a deficient number, since it is larger than the sum of its proper divisors (2161431).

28098421 is a wasteful number, since it uses less digits than its factorization.

28098421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2161430.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 28098421 is about 5300.7943744311. The cubic root of 28098421 is about 304.0142717503.

The spelling of 28098421 in words is "twenty-eight million, ninety-eight thousand, four hundred twenty-one".