28249920 has 168 divisors, whose sum is σ = 103062024. Its totient is φ = 7077888.

The previous prime is 28249919. The next prime is 28249939. The reversal of 28249920 is 2994282.

It can be written as a sum of positive squares in 4 ways, for example, as 15116544 + 13133376 = 3888^2 + 3624^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 48672 + ... + 49248.

Almost surely, 2^28249920 is an apocalyptic number.

28249920 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 28249920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (51531012).

28249920 is an abundant number, since it is smaller than the sum of its proper divisors (74812104).

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

28249920 is a wasteful number, since it uses less digits than its factorization.

28249920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 617 (or 604 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 28249920 is about 5315.0653805950. The cubic root of 28249920 is about 304.5596799555.

The spelling of 28249920 in words is "twenty-eight million, two hundred forty-nine thousand, nine hundred twenty".