28545221 has 2 divisors, whose sum is σ = 28545222. Its totient is φ = 28545220.

The previous prime is 28545211. The next prime is 28545233. The reversal of 28545221 is 12254582.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15484225 + 13060996 = 3935^2 + 3614^2 .

It is a cyclic number.

It is not a de Polignac number, because 28545221 - 2²² = 24350917 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28545211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14272610 + 14272611.

It is an arithmetic number, because the mean of its divisors is an integer number (14272611).

Almost surely, 2^28545221 is an apocalyptic number.

It is an amenable number.

28545221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28545221 is an equidigital number, since it uses as much as digits as its factorization.

28545221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6400, while the sum is 29.

The square root of 28545221 is about 5342.7727819925. The cubic root of 28545221 is about 305.6172075609.

The spelling of 28545221 in words is "twenty-eight million, five hundred forty-five thousand, two hundred twenty-one".