28021978120 has 64 divisors (see below), whose sum is σ = 65382520320. Its totient is φ = 10799910144.

The previous prime is 28021978099. The next prime is 28021978123. The reversal of 28021978120 is 2187912082.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (28021978123) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60529 + ... + 244351.

It is an arithmetic number, because the mean of its divisors is an integer number (1021601880).

Almost surely, 2^28021978120 is an apocalyptic number.

28021978120 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 28021978120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32691260160).

28021978120 is an abundant number, since it is smaller than the sum of its proper divisors (37360542200).

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

28021978120 is a wasteful number, since it uses less digits than its factorization.

28021978120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183974 (or 183970 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 40.

The spelling of 28021978120 in words is "twenty-eight billion, twenty-one million, nine hundred seventy-eight thousand, one hundred twenty".