28307621 has 2 divisors, whose sum is σ = 28307622. Its totient is φ = 28307620.

The previous prime is 28307611. The next prime is 28307633. The reversal of 28307621 is 12670382.

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., 24750625 + 3556996 = 4975^2 + 1886^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28307621 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p_1759412 and since 28307621 and 1759412 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28307611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14153810 + 14153811.

It is an arithmetic number, because the mean of its divisors is an integer number (14153811).

Almost surely, 2^28307621 is an apocalyptic number.

It is an amenable number.

28307621 is a deficient number, since it is larger than the sum of its proper divisors (1).

28307621 is an equidigital number, since it uses as much as digits as its factorization.

28307621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 28307621 is about 5320.4906728609. The cubic root of 28307621 is about 304.7668952560.

The spelling of 28307621 in words is "twenty-eight million, three hundred seven thousand, six hundred twenty-one".