28729440 has 144 divisors (see below), whose sum is σ = 99773856. Its totient is φ = 7526400.

The previous prime is 28729433. The next prime is 28729447. The reversal of 28729440 is 4492782.

It is an interprime number because it is at equal distance from previous prime (28729433) and next prime (28729447).

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a junction number, because it is equal to n+sod(n) for n = 28729395 and 28729404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28729447) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 102100 + ... + 102380.

It is an arithmetic number, because the mean of its divisors is an integer number (692874).

Almost surely, 2^28729440 is an apocalyptic number.

28729440 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 28729440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49886928).

28729440 is an abundant number, since it is smaller than the sum of its proper divisors (71044416).

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

28729440 is a wasteful number, since it uses less digits than its factorization.

28729440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373 (or 362 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 28729440 is about 5359.9850746061. The cubic root of 28729440 is about 306.2732404965.

The spelling of 28729440 in words is "twenty-eight million, seven hundred twenty-nine thousand, four hundred forty".