21727705 has 4 divisors (see below), whose sum is σ = 26073252. Its totient is φ = 17382160.

The previous prime is 21727703. The next prime is 21727711. The reversal of 21727705 is 50772712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3297856 + 18429849 = 1816^2 + 4293^2 .

It is not a de Polignac number, because 21727705 - 2¹ = 21727703 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21727703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2172766 + ... + 2172775.

It is an arithmetic number, because the mean of its divisors is an integer number (6518313).

Almost surely, 2^21727705 is an apocalyptic number.

It is an amenable number.

21727705 is a deficient number, since it is larger than the sum of its proper divisors (4345547).

21727705 is an equidigital number, since it uses as much as digits as its factorization.

21727705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4345546.

The product of its (nonzero) digits is 6860, while the sum is 31.

The square root of 21727705 is about 4661.2986387916. The cubic root of 21727705 is about 279.0430983039.

The spelling of 21727705 in words is "twenty-one million, seven hundred twenty-seven thousand, seven hundred five".