28021501 has 2 divisors, whose sum is σ = 28021502. Its totient is φ = 28021500.

The previous prime is 28021421. The next prime is 28021507. The reversal of 28021501 is 10512082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21846276 + 6175225 = 4674^2 + 2485^2 .

It is a cyclic number.

It is not a de Polignac number, because 28021501 - 2⁷ = 28021373 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 (28021507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14010750 + 14010751.

It is an arithmetic number, because the mean of its divisors is an integer number (14010751).

Almost surely, 2^28021501 is an apocalyptic number.

It is an amenable number.

28021501 is a deficient number, since it is larger than the sum of its proper divisors (1).

28021501 is an equidigital number, since it uses as much as digits as its factorization.

28021501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 28021501 is about 5293.5338857893. The cubic root of 28021501 is about 303.7366031337.

Adding to 28021501 its reverse (10512082), we get a palindrome (38533583).

The spelling of 28021501 in words is "twenty-eight million, twenty-one thousand, five hundred one".