21326440 has 32 divisors (see below), whose sum is σ = 48120480. Its totient is φ = 8506432.

The previous prime is 21326429. The next prime is 21326441. The reversal of 21326440 is 4462312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21326441) 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 7 ways as a sum of consecutive naturals, for example, 22047 + ... + 22993.

It is an arithmetic number, because the mean of its divisors is an integer number (1503765).

Almost surely, 2^21326440 is an apocalyptic number.

21326440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21326440 is an abundant number, since it is smaller than the sum of its proper divisors (26794040).

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

21326440 is a wasteful number, since it uses less digits than its factorization.

21326440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521 (or 1517 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 21326440 is about 4618.0558680033. The cubic root of 21326440 is about 277.3146342073.

Adding to 21326440 its reverse (4462312), we get a palindrome (25788752).

The spelling of 21326440 in words is "twenty-one million, three hundred twenty-six thousand, four hundred forty".