28921320 has 128 divisors (see below), whose sum is σ = 98208000. Its totient is φ = 7568640.

The previous prime is 28921307. The next prime is 28921337. The reversal of 28921320 is 2312982.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65661 + ... + 66099.

It is an arithmetic number, because the mean of its divisors is an integer number (767250).

Almost surely, 2^28921320 is an apocalyptic number.

28921320 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 28921320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49104000).

28921320 is an abundant number, since it is smaller than the sum of its proper divisors (69286680).

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

28921320 is a wasteful number, since it uses less digits than its factorization.

28921320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520 (or 510 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 28921320 is about 5377.8545908197. The cubic root of 28921320 is about 306.9535804644.

It can be divided in two parts, 28921 and 320, that added together give a square (29241 = 171²).

The spelling of 28921320 in words is "twenty-eight million, nine hundred twenty-one thousand, three hundred twenty".