21743840 has 24 divisors (see below), whose sum is σ = 51370200. Its totient is φ = 8697472.

The previous prime is 21743837. The next prime is 21743861. The reversal of 21743840 is 4834712.

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 3 ways as a sum of consecutive naturals, for example, 67790 + ... + 68109.

It is an arithmetic number, because the mean of its divisors is an integer number (2140425).

Almost surely, 2^21743840 is an apocalyptic number.

21743840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21743840 is an abundant number, since it is smaller than the sum of its proper divisors (29626360).

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

21743840 is a wasteful number, since it uses less digits than its factorization.

21743840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135914 (or 135906 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 21743840 is about 4663.0290584555. The cubic root of 21743840 is about 279.1121537083.

The spelling of 21743840 in words is "twenty-one million, seven hundred forty-three thousand, eight hundred forty".