21045413 has 4 divisors (see below), whose sum is σ = 21161868. Its totient is φ = 20928960.

The previous prime is 21045377. The next prime is 21045421. The reversal of 21045413 is 31454012.

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 8421604 + 12623809 = 2902^2 + 3553^2 .

It is a cyclic number.

It is not a de Polignac number, because 21045413 - 2¹⁰ = 21044389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045433) 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, 57956 + ... + 58317.

It is an arithmetic number, because the mean of its divisors is an integer number (5290467).

Almost surely, 2^21045413 is an apocalyptic number.

It is an amenable number.

21045413 is a deficient number, since it is larger than the sum of its proper divisors (116455).

21045413 is a wasteful number, since it uses less digits than its factorization.

21045413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116454.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21045413 is about 4587.5279835659. The cubic root of 21045413 is about 276.0911490937.

Adding to 21045413 its reverse (31454012), we get a palindrome (52499425).

The spelling of 21045413 in words is "twenty-one million, forty-five thousand, four hundred thirteen".