21330672 has 80 divisors (see below), whose sum is σ = 61067520. Its totient is φ = 6361600.

The previous prime is 21330649. The next prime is 21330679. The reversal of 21330672 is 27603312.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330679) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 37204 + ... + 37772.

It is an arithmetic number, because the mean of its divisors is an integer number (763344).

Almost surely, 2^21330672 is an apocalyptic number.

21330672 is a gapful number since it is divisible by the number (22) 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 21330672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30533760).

21330672 is an abundant number, since it is smaller than the sum of its proper divisors (39736848).

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

21330672 is a wasteful number, since it uses less digits than its factorization.

21330672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662 (or 656 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 24.

The square root of 21330672 is about 4618.5140467471. The cubic root of 21330672 is about 277.3329763514.

Adding to 21330672 its reverse (27603312), we get a palindrome (48933984).

It can be divided in two parts, 213 and 30672, that multiplied together give a square (6533136 = 2556²).

The spelling of 21330672 in words is "twenty-one million, three hundred thirty thousand, six hundred seventy-two".