28663021 has 4 divisors (see below), whose sum is σ = 28745500. Its totient is φ = 28580544.

The previous prime is 28663007. The next prime is 28663027. The reversal of 28663021 is 12036682.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9696996 + 18966025 = 3114^2 + 4355^2 .

It is a cyclic number.

It is not a de Polignac number, because 28663021 - 2⁵ = 28662989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28663027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40716 + ... + 41413.

It is an arithmetic number, because the mean of its divisors is an integer number (7186375).

Almost surely, 2^28663021 is an apocalyptic number.

It is an amenable number.

28663021 is a deficient number, since it is larger than the sum of its proper divisors (82479).

28663021 is an equidigital number, since it uses as much as digits as its factorization.

28663021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82478.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 28663021 is about 5353.7856699722. The cubic root of 28663021 is about 306.0370361141.

The spelling of 28663021 in words is "twenty-eight million, six hundred sixty-three thousand, twenty-one".