28220404 has 12 divisors (see below), whose sum is σ = 49895524. Its totient is φ = 13964544.

The previous prime is 28220383. The next prime is 28220407. The reversal of 28220404 is 40402282.

It can be written as a sum of positive squares in 2 ways, for example, as 20268004 + 7952400 = 4502^2 + 2820^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28220407) 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, 35979 + ... + 36754.

Almost surely, 2^28220404 is an apocalyptic number.

It is an amenable number.

28220404 is a deficient number, since it is larger than the sum of its proper divisors (21675120).

28220404 is a wasteful number, since it uses less digits than its factorization.

28220404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72834 (or 72832 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 22.

The square root of 28220404 is about 5312.2880193002. The cubic root of 28220404 is about 304.4535732705.

Adding to 28220404 its reverse (40402282), we get a palindrome (68622686).

The spelling of 28220404 in words is "twenty-eight million, two hundred twenty thousand, four hundred four".