28781532 has 72 divisors (see below), whose sum is σ = 79344720. Its totient is φ = 8743680.

The previous prime is 28781509. The next prime is 28781537. The reversal of 28781532 is 23518782.

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 (28781537) 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, 41307 + ... + 41997.

It is an arithmetic number, because the mean of its divisors is an integer number (1102010).

Almost surely, 2^28781532 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 28781532, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39672360).

28781532 is an abundant number, since it is smaller than the sum of its proper divisors (50563188).

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

28781532 is a wasteful number, since it uses less digits than its factorization.

28781532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 803 (or 798 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 28781532 is about 5364.8422157599. The cubic root of 28781532 is about 306.4582394912.

The spelling of 28781532 in words is "twenty-eight million, seven hundred eighty-one thousand, five hundred thirty-two".