21320105 has 4 divisors (see below), whose sum is σ = 25584132. Its totient is φ = 17056080.

The previous prime is 21320099. The next prime is 21320107. The reversal of 21320105 is 50102312.

It is a happy number.

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 9320809 + 11999296 = 3053^2 + 3464^2 .

It is not a de Polignac number, because 21320105 - 2⁸ = 21319849 is a prime.

It is a super-2 number, since 2×21320105² = 909093754422050, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21320105.

It is not an unprimeable number, because it can be changed into a prime (21320107) 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, 2132006 + ... + 2132015.

It is an arithmetic number, because the mean of its divisors is an integer number (6396033).

Almost surely, 2^21320105 is an apocalyptic number.

It is an amenable number.

21320105 is a deficient number, since it is larger than the sum of its proper divisors (4264027).

21320105 is an equidigital number, since it uses as much as digits as its factorization.

21320105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4264026.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21320105 is about 4617.3699223692. The cubic root of 21320105 is about 277.2871727996.

Adding to 21320105 its reverse (50102312), we get a palindrome (71422417).

The spelling of 21320105 in words is "twenty-one million, three hundred twenty thousand, one hundred five".