28003993920 has 840 divisors, whose sum is σ = 122789829096. Its totient is φ = 6019743744.

The previous prime is 28003993867. The next prime is 28003993921. The reversal of 28003993920 is 2939930082.

It can be written as a sum of positive squares in 4 ways, for example, as 15372032256 + 12631961664 = 123984^2 + 112392^2 .

It is a tau number, because it is divible by the number of its divisors (840).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28003993921) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 21590712 + ... + 21592008.

Almost surely, 2^28003993920 is an apocalyptic number.

28003993920 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 28003993920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (61394914548).

28003993920 is an abundant number, since it is smaller than the sum of its proper divisors (94785835176).

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

28003993920 is a wasteful number, since it uses less digits than its factorization.

28003993920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1357 (or 1331 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 45.

The spelling of 28003993920 in words is "twenty-eight billion, three million, nine hundred ninety-three thousand, nine hundred twenty".