21743809 has 8 divisors (see below), whose sum is σ = 23883840. Its totient is φ = 19703376.

The previous prime is 21743807. The next prime is 21743831. The reversal of 21743809 is 90834712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21743809 - 2¹ = 21743807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21743807) 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 7 ways as a sum of consecutive naturals, for example, 24442 + ... + 25315.

It is an arithmetic number, because the mean of its divisors is an integer number (2985480).

Almost surely, 2^21743809 is an apocalyptic number.

It is an amenable number.

21743809 is a deficient number, since it is larger than the sum of its proper divisors (2140031).

21743809 is a wasteful number, since it uses less digits than its factorization.

21743809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49799.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 21743809 is about 4663.0257344347. The cubic root of 21743809 is about 279.1120210657.

The spelling of 21743809 in words is "twenty-one million, seven hundred forty-three thousand, eight hundred nine".