21911040 has 160 divisors (see below), whose sum is σ = 78075360. Its totient is φ = 5824512.

The previous prime is 21911027. The next prime is 21911059. The reversal of 21911040 is 4011912.

It is a tau number, because it is divible by the number of its divisors (160).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68962 + ... + 69278.

It is an arithmetic number, because the mean of its divisors is an integer number (487971).

Almost surely, 2^21911040 is an apocalyptic number.

21911040 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 21911040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39037680).

21911040 is an abundant number, since it is smaller than the sum of its proper divisors (56164320).

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

21911040 is an equidigital number, since it uses as much as digits as its factorization.

21911040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349 (or 327 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21911040 is about 4680.9229859078. The cubic root of 21911040 is about 279.8257419131.

Adding to 21911040 its reverse (4011912), we get a palindrome (25922952).

The spelling of 21911040 in words is "twenty-one million, nine hundred eleven thousand, forty".