28129644 has 72 divisors (see below), whose sum is σ = 75714912. Its totient is φ = 8785920.

The previous prime is 28129643. The next prime is 28129663. The reversal of 28129644 is 44692182.

28129644 is a `hidden beast` number, since 2 + 8 + 1 + 2 + 9 + 644 = 666.

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 = 28129599 and 28129608.

It is not an unprimeable number, because it can be changed into a prime (28129643) 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, 43564 + ... + 44204.

It is an arithmetic number, because the mean of its divisors is an integer number (1051596).

Almost surely, 2^28129644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28129644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37857456).

28129644 is an abundant number, since it is smaller than the sum of its proper divisors (47585268).

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

28129644 is a wasteful number, since it uses less digits than its factorization.

28129644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727 (or 722 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 28129644 is about 5303.7386813455. The cubic root of 28129644 is about 304.1268370774.

The spelling of 28129644 in words is "twenty-eight million, one hundred twenty-nine thousand, six hundred forty-four".