28800721 has 2 divisors, whose sum is σ = 28800722. Its totient is φ = 28800720.

The previous prime is 28800719. The next prime is 28800749. The reversal of 28800721 is 12700882.

It is an a-pointer prime, because the next prime (28800749) can be obtained adding 28800721 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17943696 + 10857025 = 4236^2 + 3295^2 .

It is a cyclic number.

It is not a de Polignac number, because 28800721 - 2¹ = 28800719 is a prime.

Together with 28800719, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 28800721.

It is not a weakly prime, because it can be changed into another prime (28800701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14400360 + 14400361.

It is an arithmetic number, because the mean of its divisors is an integer number (14400361).

Almost surely, 2^28800721 is an apocalyptic number.

It is an amenable number.

28800721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28800721 is an equidigital number, since it uses as much as digits as its factorization.

28800721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 28800721 is about 5366.6303207879. The cubic root of 28800721 is about 306.5263308486.

The spelling of 28800721 in words is "twenty-eight million, eight hundred thousand, seven hundred twenty-one".