28404221 has 8 divisors (see below), whose sum is σ = 29971200. Its totient is φ = 26844480.

The previous prime is 28404203. The next prime is 28404239. The reversal of 28404221 is 12240482.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28404203) and next prime (28404239).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28404221 - 2¹⁰ = 28403197 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 (28404251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7541 + ... + 10661.

It is an arithmetic number, because the mean of its divisors is an integer number (3746400).

Almost surely, 2^28404221 is an apocalyptic number.

It is an amenable number.

28404221 is a deficient number, since it is larger than the sum of its proper divisors (1566979).

28404221 is a wasteful number, since it uses less digits than its factorization.

28404221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3619.

The product of its (nonzero) digits is 1024, while the sum is 23.

The square root of 28404221 is about 5329.5610513437. The cubic root of 28404221 is about 305.1131748767.

The spelling of 28404221 in words is "twenty-eight million, four hundred four thousand, two hundred twenty-one".