21111440 has 40 divisors (see below), whose sum is σ = 56097600. Its totient is φ = 7238016.

The previous prime is 21111397. The next prime is 21111457. The reversal of 21111440 is 4411112.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (14).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18290 + ... + 19409.

It is an arithmetic number, because the mean of its divisors is an integer number (1402440).

Almost surely, 2^21111440 is an apocalyptic number.

21111440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111440 is an abundant number, since it is smaller than the sum of its proper divisors (34986160).

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

21111440 is a wasteful number, since it uses less digits than its factorization.

21111440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37719 (or 37713 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 21111440 is about 4594.7187073857. The cubic root of 21111440 is about 276.3795799477.

Adding to 21111440 its reverse (4411112), we get a palindrome (25522552).

The spelling of 21111440 in words is "twenty-one million, one hundred eleven thousand, four hundred forty".