28220405 has 8 divisors (see below), whose sum is σ = 33928632. Its totient is φ = 22533568.

The previous prime is 28220383. The next prime is 28220407. The reversal of 28220405 is 50402282.

It can be written as a sum of positive squares in 4 ways, for example, as 1615441 + 26604964 = 1271^2 + 5158^2 .

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 28220405 - 2¹⁰ = 28219381 is a prime.

It is a Duffinian number.

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 pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2282 + ... + 7851.

It is an arithmetic number, because the mean of its divisors is an integer number (4241079).

Almost surely, 2^28220405 is an apocalyptic number.

It is an amenable number.

28220405 is a deficient number, since it is larger than the sum of its proper divisors (5708227).

28220405 is a wasteful number, since it uses less digits than its factorization.

28220405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10695.

The product of its (nonzero) digits is 1280, while the sum is 23.

The square root of 28220405 is about 5312.2881134216. The cubic root of 28220405 is about 304.4535768666.

Adding to 28220405 its reverse (50402282), we get a palindrome (78622687).

The spelling of 28220405 in words is "twenty-eight million, two hundred twenty thousand, four hundred five".