28249421 has 4 divisors (see below), whose sum is σ = 28508700. Its totient is φ = 27990144.

The previous prime is 28249379. The next prime is 28249423. The reversal of 28249421 is 12494282.

It is a happy number.

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 19758025 + 8491396 = 4445^2 + 2914^2 .

It is a cyclic number.

It is not a de Polignac number, because 28249421 - 2¹⁰ = 28248397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28249423) 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, 129476 + ... + 129693.

It is an arithmetic number, because the mean of its divisors is an integer number (7127175).

Almost surely, 2^28249421 is an apocalyptic number.

It is an amenable number.

28249421 is a deficient number, since it is larger than the sum of its proper divisors (259279).

28249421 is a wasteful number, since it uses less digits than its factorization.

28249421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259278.

The product of its digits is 9216, while the sum is 32.

The square root of 28249421 is about 5315.0184383500. The cubic root of 28249421 is about 304.5578867212.

The spelling of 28249421 in words is "twenty-eight million, two hundred forty-nine thousand, four hundred twenty-one".