28228621 has 2 divisors, whose sum is σ = 28228622. Its totient is φ = 28228620.

The previous prime is 28228573. The next prime is 28228639. The reversal of 28228621 is 12682282.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26894596 + 1334025 = 5186^2 + 1155^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28228621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28228691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14114310 + 14114311.

It is an arithmetic number, because the mean of its divisors is an integer number (14114311).

Almost surely, 2^28228621 is an apocalyptic number.

It is an amenable number.

28228621 is a deficient number, since it is larger than the sum of its proper divisors (1).

28228621 is an equidigital number, since it uses as much as digits as its factorization.

28228621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6144, while the sum is 31.

The square root of 28228621 is about 5313.0613585766. The cubic root of 28228621 is about 304.4831198856.

The spelling of 28228621 in words is "twenty-eight million, two hundred twenty-eight thousand, six hundred twenty-one".