21060605 has 4 divisors (see below), whose sum is σ = 25272732. Its totient is φ = 16848480.

The previous prime is 21060553. The next prime is 21060619. The reversal of 21060605 is 50606012.

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 5982916 + 15077689 = 2446^2 + 3883^2 .

It is not a de Polignac number, because 21060605 - 2⁶ = 21060541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2106056 + ... + 2106065.

It is an arithmetic number, because the mean of its divisors is an integer number (6318183).

Almost surely, 2^21060605 is an apocalyptic number.

It is an amenable number.

21060605 is a deficient number, since it is larger than the sum of its proper divisors (4212127).

21060605 is an equidigital number, since it uses as much as digits as its factorization.

21060605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4212126.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21060605 is about 4589.1834785722. The cubic root of 21060605 is about 276.1575668586.

Adding to 21060605 its reverse (50606012), we get a palindrome (71666617).

The spelling of 21060605 in words is "twenty-one million, sixty thousand, six hundred five".