21343680 has 84 divisors (see below), whose sum is σ = 73423272. Its totient is φ = 5690880.

The previous prime is 21343661. The next prime is 21343691. The reversal of 21343680 is 8634312.

It is a happy number.

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 11 ways as a sum of consecutive naturals, for example, 826 + ... + 6585.

Almost surely, 2^21343680 is an apocalyptic number.

21343680 is a gapful number since it is divisible by the number (20) 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 21343680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36711636).

21343680 is an abundant number, since it is smaller than the sum of its proper divisors (52079592).

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

21343680 is a wasteful number, since it uses less digits than its factorization.

21343680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7434 (or 7421 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21343680 is about 4619.9220772649. The cubic root of 21343680 is about 277.3893398559.

Adding to 21343680 its reverse (8634312), we get a palindrome (29977992).

The spelling of 21343680 in words is "twenty-one million, three hundred forty-three thousand, six hundred eighty".