28773221 has 2 divisors, whose sum is σ = 28773222. Its totient is φ = 28773220.

The previous prime is 28773209. The next prime is 28773257. The reversal of 28773221 is 12237782.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21808900 + 6964321 = 4670^2 + 2639^2 .

It is a cyclic number.

It is not a de Polignac number, because 28773221 - 2¹⁰ = 28772197 is a prime.

It is a Sophie Germain prime.

It is a Chen 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 (28773281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14386610 + 14386611.

It is an arithmetic number, because the mean of its divisors is an integer number (14386611).

Almost surely, 2^28773221 is an apocalyptic number.

It is an amenable number.

28773221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28773221 is an equidigital number, since it uses as much as digits as its factorization.

28773221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9408, while the sum is 32.

The square root of 28773221 is about 5364.0675797383. The cubic root of 28773221 is about 306.4287388653.

The spelling of 28773221 in words is "twenty-eight million, seven hundred seventy-three thousand, two hundred twenty-one".