20911840 has 24 divisors (see below), whose sum is σ = 49404600. Its totient is φ = 8364672.

The previous prime is 20911823. The next prime is 20911867. The reversal of 20911840 is 4811902.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65190 + ... + 65509.

It is an arithmetic number, because the mean of its divisors is an integer number (2058525).

Almost surely, 2^20911840 is an apocalyptic number.

20911840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20911840 is an abundant number, since it is smaller than the sum of its proper divisors (28492760).

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

20911840 is a wasteful number, since it uses less digits than its factorization.

20911840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130714 (or 130706 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 20911840 is about 4572.9465336914. The cubic root of 20911840 is about 275.5058019009.

The spelling of 20911840 in words is "twenty million, nine hundred eleven thousand, eight hundred forty".