21254605 has 8 divisors (see below), whose sum is σ = 26127864. Its totient is φ = 16588800.

The previous prime is 21254581. The next prime is 21254617. The reversal of 21254605 is 50645212.

It can be written as a sum of positive squares in 4 ways, for example, as 149769 + 21104836 = 387^2 + 4594^2 .

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

It is not a de Polignac number, because 21254605 - 2¹⁷ = 21123533 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 21254605.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 51636 + ... + 52045.

It is an arithmetic number, because the mean of its divisors is an integer number (3265983).

Almost surely, 2^21254605 is an apocalyptic number.

It is an amenable number.

21254605 is a deficient number, since it is larger than the sum of its proper divisors (4873259).

21254605 is a wasteful number, since it uses less digits than its factorization.

21254605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103727.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 21254605 is about 4610.2716839683. The cubic root of 21254605 is about 277.0029193348.

Adding to 21254605 its reverse (50645212), we get a palindrome (71899817).

The spelling of 21254605 in words is "twenty-one million, two hundred fifty-four thousand, six hundred five".