21333240 has 64 divisors (see below), whose sum is σ = 71114400. Its totient is φ = 5688576.

The previous prime is 21333199. The next prime is 21333251. The reversal of 21333240 is 4233312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 8797 + ... + 10956.

Almost surely, 2^21333240 is an apocalyptic number.

21333240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21333240 is an abundant number, since it is smaller than the sum of its proper divisors (49781160).

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

21333240 is a wasteful number, since it uses less digits than its factorization.

21333240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19773 (or 19763 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 18.

The square root of 21333240 is about 4618.7920498762. The cubic root of 21333240 is about 277.3441052789.

Adding to 21333240 its reverse (4233312), we get a palindrome (25566552).

The spelling of 21333240 in words is "twenty-one million, three hundred thirty-three thousand, two hundred forty".