28919920 has 20 divisors (see below), whose sum is σ = 67239000. Its totient is φ = 11567936.

The previous prime is 28919911. The next prime is 28919959. The reversal of 28919920 is 2991982.

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

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180670 + ... + 180829.

It is an arithmetic number, because the mean of its divisors is an integer number (3361950).

Almost surely, 2^28919920 is an apocalyptic number.

28919920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28919920 is an abundant number, since it is smaller than the sum of its proper divisors (38319080).

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

28919920 is a wasteful number, since it uses less digits than its factorization.

28919920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361512 (or 361506 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 28919920 is about 5377.7244258143. The cubic root of 28919920 is about 306.9486274637.

The spelling of 28919920 in words is "twenty-eight million, nine hundred nineteen thousand, nine hundred twenty".