28139888 has 40 divisors (see below), whose sum is σ = 63769728. Its totient is φ = 11777472.

The previous prime is 28139863. The next prime is 28139897. The reversal of 28139888 is 88893182.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1895 + ... + 7737.

Almost surely, 2^28139888 is an apocalyptic number.

28139888 is a gapful number since it is divisible by the number (28) 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 28139888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31884864).

28139888 is an abundant number, since it is smaller than the sum of its proper divisors (35629840).

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

28139888 is a wasteful number, since it uses less digits than its factorization.

28139888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5901 (or 5895 counting only the distinct ones).

The product of its digits is 221184, while the sum is 47.

The square root of 28139888 is about 5304.7043272929. The cubic root of 28139888 is about 304.1637506528.

The spelling of 28139888 in words is "twenty-eight million, one hundred thirty-nine thousand, eight hundred eighty-eight".