28215400 has 48 divisors (see below), whose sum is σ = 66558240. Its totient is φ = 11121600.

The previous prime is 28215389. The next prime is 28215401. The reversal of 28215400 is 451282.

It is a super-2 number, since 2×28215400² = 1592217594320000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28215401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13207 + ... + 15193.

It is an arithmetic number, because the mean of its divisors is an integer number (1386630).

Almost surely, 2^28215400 is an apocalyptic number.

28215400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28215400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33279120).

28215400 is an abundant number, since it is smaller than the sum of its proper divisors (38342840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28215400 is a wasteful number, since it uses less digits than its factorization.

28215400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2074 (or 2065 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 28215400 is about 5311.8170149206. The cubic root of 28215400 is about 304.4355771221.

Adding to 28215400 its reverse (451282), we get a palindrome (28666682).

The spelling of 28215400 in words is "twenty-eight million, two hundred fifteen thousand, four hundred".