21045013 has 8 divisors (see below), whose sum is σ = 23518656. Its totient is φ = 18664800.

The previous prime is 21044999. The next prime is 21045041. The reversal of 21045013 is 31054012.

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

It is not a de Polignac number, because 21045013 - 2¹⁷ = 20913941 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 (21045053) 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 7 ways as a sum of consecutive naturals, for example, 22881 + ... + 23782.

It is an arithmetic number, because the mean of its divisors is an integer number (2939832).

Almost surely, 2^21045013 is an apocalyptic number.

It is an amenable number.

21045013 is a deficient number, since it is larger than the sum of its proper divisors (2473643).

21045013 is a wasteful number, since it uses less digits than its factorization.

21045013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46715.

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

The square root of 21045013 is about 4587.4843868944. The cubic root of 21045013 is about 276.0893999056.

Adding to 21045013 its reverse (31054012), we get a palindrome (52099025).

It can be divided in two parts, 2104 and 5013, that added together give a palindrome (7117).

The spelling of 21045013 in words is "twenty-one million, forty-five thousand, thirteen".