28688220 has 72 divisors (see below), whose sum is σ = 94938480. Its totient is φ = 6954240.

The previous prime is 28688213. The next prime is 28688227. The reversal of 28688220 is 2288682.

It is an interprime number because it is at equal distance from previous prime (28688213) and next prime (28688227).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28688227) 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 23 ways as a sum of consecutive naturals, for example, 5265 + ... + 9224.

It is an arithmetic number, because the mean of its divisors is an integer number (1318590).

Almost surely, 2^28688220 is an apocalyptic number.

28688220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28688220 is an abundant number, since it is smaller than the sum of its proper divisors (66250260).

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

28688220 is a wasteful number, since it uses less digits than its factorization.

28688220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14515 (or 14510 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The square root of 28688220 is about 5356.1385344294. The cubic root of 28688220 is about 306.1266936609.

The spelling of 28688220 in words is "twenty-eight million, six hundred eighty-eight thousand, two hundred twenty".