28025021 has 4 divisors (see below), whose sum is σ = 28782492. Its totient is φ = 27267552.

The previous prime is 28025009. The next prime is 28025029. The reversal of 28025021 is 12052082.

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 12924025 + 15100996 = 3595^2 + 3886^2 .

It is a cyclic number.

It is not a de Polignac number, because 28025021 - 2¹⁴ = 28008637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28024984 and 28025002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28025029) 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, 378680 + ... + 378753.

It is an arithmetic number, because the mean of its divisors is an integer number (7195623).

Almost surely, 2^28025021 is an apocalyptic number.

It is an amenable number.

28025021 is a deficient number, since it is larger than the sum of its proper divisors (757471).

28025021 is an equidigital number, since it uses as much as digits as its factorization.

28025021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 757470.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 28025021 is about 5293.8663564544. The cubic root of 28025021 is about 303.7493208450.

The spelling of 28025021 in words is "twenty-eight million, twenty-five thousand, twenty-one".