21035705 has 4 divisors (see below), whose sum is σ = 25242852. Its totient is φ = 16828560.

The previous prime is 21035699. The next prime is 21035737. The reversal of 21035705 is 50753012.

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 15578809 + 5456896 = 3947^2 + 2336^2 .

It is not a de Polignac number, because 21035705 - 2⁸ = 21035449 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 2103566 + ... + 2103575.

It is an arithmetic number, because the mean of its divisors is an integer number (6310713).

Almost surely, 2^21035705 is an apocalyptic number.

It is an amenable number.

21035705 is a deficient number, since it is larger than the sum of its proper divisors (4207147).

21035705 is an equidigital number, since it uses as much as digits as its factorization.

21035705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4207146.

The product of its (nonzero) digits is 1050, while the sum is 23.

The square root of 21035705 is about 4586.4697753283. The cubic root of 21035705 is about 276.0486900377.

Adding to 21035705 its reverse (50753012), we get a palindrome (71788717).

The spelling of 21035705 in words is "twenty-one million, thirty-five thousand, seven hundred five".