21190440 has 128 divisors (see below), whose sum is σ = 67132800. Its totient is φ = 5345280.

The previous prime is 21190427. The next prime is 21190441. The reversal of 21190440 is 4409112.

It is not an unprimeable number, because it can be changed into a prime (21190441) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 290244 + ... + 290316.

It is an arithmetic number, because the mean of its divisors is an integer number (524475).

Almost surely, 2^21190440 is an apocalyptic number.

21190440 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 21190440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33566400).

21190440 is an abundant number, since it is smaller than the sum of its proper divisors (45942360).

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

21190440 is a wasteful number, since it uses less digits than its factorization.

21190440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187 (or 183 counting only the distinct ones).

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

The square root of 21190440 is about 4603.3075065653. The cubic root of 21190440 is about 276.7238926157.

Adding to 21190440 its reverse (4409112), we get a palindrome (25599552).

The spelling of 21190440 in words is "twenty-one million, one hundred ninety thousand, four hundred forty".