21705943 has 8 divisors (see below), whose sum is σ = 25086240. Its totient is φ = 18395520.

The previous prime is 21705899. The next prime is 21705947. The reversal of 21705943 is 34950712.

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 21705943 - 2¹³ = 21697751 is a prime.

It is a super-2 number, since 2×21705943² = 942295923038498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705947) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16798 + ... + 18043.

It is an arithmetic number, because the mean of its divisors is an integer number (3135780).

Almost surely, 2^21705943 is an apocalyptic number.

21705943 is a deficient number, since it is larger than the sum of its proper divisors (3380297).

21705943 is an equidigital number, since it uses as much as digits as its factorization.

21705943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34937.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21705943 is about 4658.9637259803. The cubic root of 21705943 is about 278.9499060039.

The spelling of 21705943 in words is "twenty-one million, seven hundred five thousand, nine hundred forty-three".