21343840 has 192 divisors, whose sum is σ = 65318400. Its totient is φ = 6414336.

The previous prime is 21343831. The next prime is 21343843. The reversal of 21343840 is 4834312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21343843) 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 31 ways as a sum of consecutive naturals, for example, 361731 + ... + 361789.

It is an arithmetic number, because the mean of its divisors is an integer number (340200).

Almost surely, 2^21343840 is an apocalyptic number.

21343840 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 21343840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32659200).

21343840 is an abundant number, since it is smaller than the sum of its proper divisors (43974560).

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

21343840 is a wasteful number, since it uses less digits than its factorization.

21343840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117 (or 109 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 21343840 is about 4619.9393935419. The cubic root of 21343840 is about 277.3900329914.

The spelling of 21343840 in words is "twenty-one million, three hundred forty-three thousand, eight hundred forty".