21286105 has 4 divisors (see below), whose sum is σ = 25543332. Its totient is φ = 17028880.

The previous prime is 21286103. The next prime is 21286117. The reversal of 21286105 is 50168212.

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 8690704 + 12595401 = 2948^2 + 3549^2 .

It is not a de Polignac number, because 21286105 - 2¹ = 21286103 is a prime.

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 21286105.

It is not an unprimeable number, because it can be changed into a prime (21286103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2128606 + ... + 2128615.

It is an arithmetic number, because the mean of its divisors is an integer number (6385833).

Almost surely, 2^21286105 is an apocalyptic number.

It is an amenable number.

21286105 is a deficient number, since it is larger than the sum of its proper divisors (4257227).

21286105 is an equidigital number, since it uses as much as digits as its factorization.

21286105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4257226.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 21286105 is about 4613.6867037110. The cubic root of 21286105 is about 277.1396941650.

The spelling of 21286105 in words is "twenty-one million, two hundred eighty-six thousand, one hundred five".