28187838 has 120 divisors (see below), whose sum is σ = 75977352. Its totient is φ = 7783776.

The previous prime is 28187807. The next prime is 28187893. The reversal of 28187838 is 83878182.

It is a happy number.

It is a super-2 number, since 2×28187838² = 1589108422228488, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28187793 and 28187802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 420681 + ... + 420747.

Almost surely, 2^28187838 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28187838, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37988676).

28187838 is an abundant number, since it is smaller than the sum of its proper divisors (47789514).

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

28187838 is a wasteful number, since it uses less digits than its factorization.

28187838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148 (or 132 counting only the distinct ones).

The product of its digits is 172032, while the sum is 45.

The square root of 28187838 is about 5309.2219769002. The cubic root of 28187838 is about 304.3364162969.

The spelling of 28187838 in words is "twenty-eight million, one hundred eighty-seven thousand, eight hundred thirty-eight".