28204221 has 8 divisors (see below), whose sum is σ = 37633824. Its totient is φ = 18788720.

The previous prime is 28204219. The next prime is 28204223. The reversal of 28204221 is 12240282.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28204219) and next prime (28204223).

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 28204221 - 2¹ = 28204219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28204223) 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, 2731 + ... + 7991.

It is an arithmetic number, because the mean of its divisors is an integer number (4704228).

Almost surely, 2^28204221 is an apocalyptic number.

It is an amenable number.

28204221 is a deficient number, since it is larger than the sum of its proper divisors (9429603).

28204221 is a wasteful number, since it uses less digits than its factorization.

28204221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7051.

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 28204221 is about 5310.7646342123. The cubic root of 28204221 is about 304.3953658087.

The spelling of 28204221 in words is "twenty-eight million, two hundred four thousand, two hundred twenty-one".