21105727 has 4 divisors (see below), whose sum is σ = 21342960. Its totient is φ = 20868496.

The previous prime is 21105709. The next prime is 21105739. The reversal of 21105727 is 72750112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21105727 - 2¹¹ = 21103679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105757) 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 3 ways as a sum of consecutive naturals, for example, 118483 + ... + 118660.

It is an arithmetic number, because the mean of its divisors is an integer number (5335740).

Almost surely, 2^21105727 is an apocalyptic number.

21105727 is a deficient number, since it is larger than the sum of its proper divisors (237233).

21105727 is an equidigital number, since it uses as much as digits as its factorization.

21105727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237232.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21105727 is about 4594.0969732908. The cubic root of 21105727 is about 276.3546471942.

Adding to 21105727 its reverse (72750112), we get a palindrome (93855839).

The spelling of 21105727 in words is "twenty-one million, one hundred five thousand, seven hundred twenty-seven".