21105707 has 8 divisors (see below), whose sum is σ = 24952800. Its totient is φ = 17466624.

The previous prime is 21105703. The next prime is 21105709. The reversal of 21105707 is 70750112.

It is a happy number.

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

It is not a de Polignac number, because 21105707 - 2² = 21105703 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21105703) 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, 51782 + ... + 52187.

It is an arithmetic number, because the mean of its divisors is an integer number (3119100).

Almost surely, 2^21105707 is an apocalyptic number.

21105707 is a deficient number, since it is larger than the sum of its proper divisors (3847093).

21105707 is a wasteful number, since it uses less digits than its factorization.

21105707 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104005.

The product of its (nonzero) digits is 490, while the sum is 23.

The square root of 21105707 is about 4594.0947965840. The cubic root of 21105707 is about 276.3545599020.

Adding to 21105707 its reverse (70750112), we get a palindrome (91855819).

It can be divided in two parts, 21105 and 707, that added together give a palindrome (21812).

The spelling of 21105707 in words is "twenty-one million, one hundred five thousand, seven hundred seven".