21062005 has 4 divisors (see below), whose sum is σ = 25274412. Its totient is φ = 16849600.

The previous prime is 21062003. The next prime is 21062017. The reversal of 21062005 is 50026012.

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 3972049 + 17089956 = 1993^2 + 4134^2 .

It is not a de Polignac number, because 21062005 - 2¹ = 21062003 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 21062005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21062003) 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, 2106196 + ... + 2106205.

It is an arithmetic number, because the mean of its divisors is an integer number (6318603).

Almost surely, 2^21062005 is an apocalyptic number.

It is an amenable number.

21062005 is a deficient number, since it is larger than the sum of its proper divisors (4212407).

21062005 is an equidigital number, since it uses as much as digits as its factorization.

21062005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4212406.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21062005 is about 4589.3360086182. The cubic root of 21062005 is about 276.1636858982.

Adding to 21062005 its reverse (50026012), we get a palindrome (71088017).

The spelling of 21062005 in words is "twenty-one million, sixty-two thousand, five".