728673821 has 2 divisors, whose sum is σ = 728673822. Its totient is φ = 728673820.

The previous prime is 728673811. The next prime is 728673851. The reversal of 728673821 is 128376827.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 694322500 + 34351321 = 26350^2 + 5861^2 .

It is an emirp because it is prime and its reverse (128376827) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 728673821 - 2¹⁴ = 728657437 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 (728673811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364336910 + 364336911.

It is an arithmetic number, because the mean of its divisors is an integer number (364336911).

Almost surely, 2^728673821 is an apocalyptic number.

It is an amenable number.

728673821 is a deficient number, since it is larger than the sum of its proper divisors (1).

728673821 is an equidigital number, since it uses as much as digits as its factorization.

728673821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 44.

The square root of 728673821 is about 26993.9589723331. The cubic root of 728673821 is about 899.8657499342.

The spelling of 728673821 in words is "seven hundred twenty-eight million, six hundred seventy-three thousand, eight hundred twenty-one".