21323240 has 32 divisors (see below), whose sum is σ = 48245760. Its totient is φ = 8481600.

The previous prime is 21323209. The next prime is 21323261. The reversal of 21323240 is 4232312.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6245 + ... + 9035.

It is an arithmetic number, because the mean of its divisors is an integer number (1507680).

Almost surely, 2^21323240 is an apocalyptic number.

21323240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21323240 is an abundant number, since it is smaller than the sum of its proper divisors (26922520).

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

21323240 is a wasteful number, since it uses less digits than its factorization.

21323240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2993 (or 2989 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21323240 is about 4617.7093888637. The cubic root of 21323240 is about 277.3007633000.

Adding to 21323240 its reverse (4232312), we get a palindrome (25555552).

The spelling of 21323240 in words is "twenty-one million, three hundred twenty-three thousand, two hundred forty".