20919808 has 80 divisors (see below), whose sum is σ = 51559200. Its totient is φ = 8257536.

The previous prime is 20919797. The next prime is 20919859. The reversal of 20919808 is 80891902.

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 7 ways as a sum of consecutive naturals, for example, 46368 + ... + 46816.

It is an arithmetic number, because the mean of its divisors is an integer number (644490).

Almost surely, 2^20919808 is an apocalyptic number.

20919808 is a gapful number since it is divisible by the number (28) 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 20919808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25779600).

20919808 is an abundant number, since it is smaller than the sum of its proper divisors (30639392).

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

20919808 is an equidigital number, since it uses as much as digits as its factorization.

20919808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487 (or 471 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 20919808 is about 4573.8176614290. The cubic root of 20919808 is about 275.5407892808.

The spelling of 20919808 in words is "twenty million, nine hundred nineteen thousand, eight hundred eight".