20911440 has 120 divisors (see below), whose sum is σ = 71522208. Its totient is φ = 5012480.

The previous prime is 20911427. The next prime is 20911463. The reversal of 20911440 is 4411902.

It is a tau number, because it is divible by the number of its divisors (120).

It is a zygodrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 234916 + ... + 235004.

Almost surely, 2^20911440 is an apocalyptic number.

20911440 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 20911440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35761104).

20911440 is an abundant number, since it is smaller than the sum of its proper divisors (50610768).

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

20911440 is a wasteful number, since it uses less digits than its factorization.

20911440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 20911440 is about 4572.9027980048. The cubic root of 20911440 is about 275.5040452720.

The spelling of 20911440 in words is "twenty million, nine hundred eleven thousand, four hundred forty".