21331040 has 24 divisors (see below), whose sum is σ = 50394960. Its totient is φ = 8532352.

The previous prime is 21331021. The next prime is 21331043. The reversal of 21331040 is 4013312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331043) 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 3 ways as a sum of consecutive naturals, for example, 66500 + ... + 66819.

It is an arithmetic number, because the mean of its divisors is an integer number (2099790).

Almost surely, 2^21331040 is an apocalyptic number.

21331040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21331040 is an abundant number, since it is smaller than the sum of its proper divisors (29063920).

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

21331040 is a wasteful number, since it uses less digits than its factorization.

21331040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133334 (or 133326 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21331040 is about 4618.5538862289. The cubic root of 21331040 is about 277.3345712058.

Adding to 21331040 its reverse (4013312), we get a palindrome (25344352).

The spelling of 21331040 in words is "twenty-one million, three hundred thirty-one thousand, forty".