28220640 has 192 divisors, whose sum is σ = 104799744. Its totient is φ = 6248448.

The previous prime is 28220639. The next prime is 28220641. The reversal of 28220640 is 4602282.

It is an interprime number because it is at equal distance from previous prime (28220639) and next prime (28220641).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 28220640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28220641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 124207 + ... + 124433.

It is an arithmetic number, because the mean of its divisors is an integer number (545832).

Almost surely, 2^28220640 is an apocalyptic number.

28220640 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 28220640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52399872).

28220640 is an abundant number, since it is smaller than the sum of its proper divisors (76579104).

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

28220640 is a wasteful number, since it uses less digits than its factorization.

28220640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 28220640 is about 5312.3102319048. The cubic root of 28220640 is about 304.4544219572.

The spelling of 28220640 in words is "twenty-eight million, two hundred twenty thousand, six hundred forty".