28198421 has 2 divisors, whose sum is σ = 28198422. Its totient is φ = 28198420.

The previous prime is 28198381. The next prime is 28198453. The reversal of 28198421 is 12489182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26635921 + 1562500 = 5161^2 + 1250^2 .

It is a cyclic number.

It is not a de Polignac number, because 28198421 - 2¹⁰ = 28197397 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28198021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14099210 + 14099211.

It is an arithmetic number, because the mean of its divisors is an integer number (14099211).

Almost surely, 2^28198421 is an apocalyptic number.

It is an amenable number.

28198421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28198421 is an equidigital number, since it uses as much as digits as its factorization.

28198421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 35.

The square root of 28198421 is about 5310.2185454085. The cubic root of 28198421 is about 304.3744987884.

The spelling of 28198421 in words is "twenty-eight million, one hundred ninety-eight thousand, four hundred twenty-one".