28131840 has 320 divisors, whose sum is σ = 111957120. Its totient is φ = 6635520.

The previous prime is 28131811. The next prime is 28131841. The reversal of 28131840 is 4813182.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (28131841) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 760302 + ... + 760338.

It is an arithmetic number, because the mean of its divisors is an integer number (349866).

Almost surely, 2^28131840 is an apocalyptic number.

28131840 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 28131840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (55978560).

28131840 is an abundant number, since it is smaller than the sum of its proper divisors (83825280).

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

28131840 is a wasteful number, since it uses less digits than its factorization.

28131840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 28131840 is about 5303.9457010795. The cubic root of 28131840 is about 304.1347509725.

The spelling of 28131840 in words is "twenty-eight million, one hundred thirty-one thousand, eight hundred forty".