21021013 has 8 divisors (see below), whose sum is σ = 22675968. Its totient is φ = 19371504.

The previous prime is 21021001. The next prime is 21021043. The reversal of 21021013 is 31012012.

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

It is a cyclic number.

It is not a de Polignac number, because 21021013 - 2⁹ = 21020501 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 (21021043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10620 + ... + 12442.

It is an arithmetic number, because the mean of its divisors is an integer number (2834496).

Almost surely, 2^21021013 is an apocalyptic number.

It is an amenable number.

21021013 is a deficient number, since it is larger than the sum of its proper divisors (1654955).

21021013 is a wasteful number, since it uses less digits than its factorization.

21021013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2723.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21021013 is about 4584.8678279750. The cubic root of 21021013 is about 275.9844080319.

Adding to 21021013 its reverse (31012012), we get a palindrome (52033025).

Subtracting 21021013 from its reverse (31012012), we obtain a palindrome (9990999).

The spelling of 21021013 in words is "twenty-one million, twenty-one thousand, thirteen".