22728821 has 2 divisors, whose sum is σ = 22728822. Its totient is φ = 22728820.

The previous prime is 22728817. The next prime is 22728851. The reversal of 22728821 is 12882722.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14668900 + 8059921 = 3830^2 + 2839^2 .

It is a cyclic number.

It is not a de Polignac number, because 22728821 - 2² = 22728817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (22728851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11364410 + 11364411.

It is an arithmetic number, because the mean of its divisors is an integer number (11364411).

Almost surely, 2^22728821 is an apocalyptic number.

It is an amenable number.

22728821 is a deficient number, since it is larger than the sum of its proper divisors (1).

22728821 is an equidigital number, since it uses as much as digits as its factorization.

22728821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7168, while the sum is 32.

The square root of 22728821 is about 4767.4753276761. The cubic root of 22728821 is about 283.2645995518.

The spelling of 22728821 in words is "twenty-two million, seven hundred twenty-eight thousand, eight hundred twenty-one".