28019920 has 20 divisors (see below), whose sum is σ = 65146500. Its totient is φ = 11207936.

The previous prime is 28019917. The next prime is 28019921. The reversal of 28019920 is 2991082.

It can be written as a sum of positive squares in 2 ways, for example, as 13366336 + 14653584 = 3656^2 + 3828^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28019921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175045 + ... + 175204.

It is an arithmetic number, because the mean of its divisors is an integer number (3257325).

Almost surely, 2^28019920 is an apocalyptic number.

28019920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28019920 is an abundant number, since it is smaller than the sum of its proper divisors (37126580).

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

28019920 is a wasteful number, since it uses less digits than its factorization.

28019920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350262 (or 350256 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 28019920 is about 5293.3845505499. The cubic root of 28019920 is about 303.7308906560.

It can be divided in two parts, 2801 and 9920, that added together give a palindrome (12721).

The spelling of 28019920 in words is "twenty-eight million, nineteen thousand, nine hundred twenty".