28181820 has 48 divisors (see below), whose sum is σ = 79873920. Its totient is φ = 7423296.

The previous prime is 28181809. The next prime is 28181837. The reversal of 28181820 is 2818182.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2151 + ... + 7809.

It is an arithmetic number, because the mean of its divisors is an integer number (1664040).

Almost surely, 2^28181820 is an apocalyptic number.

28181820 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 28181820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39936960).

28181820 is an abundant number, since it is smaller than the sum of its proper divisors (51692100).

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

28181820 is a wasteful number, since it uses less digits than its factorization.

28181820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5754 (or 5752 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 30.

The square root of 28181820 is about 5308.6551969402. The cubic root of 28181820 is about 304.3147565193.

The spelling of 28181820 in words is "twenty-eight million, one hundred eighty-one thousand, eight hundred twenty".