21030013 has 4 divisors (see below), whose sum is σ = 21104608. Its totient is φ = 20955420.

The previous prime is 21030001. The next prime is 21030043. The reversal of 21030013 is 31003012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21030013 - 2²¹ = 18932861 is a prime.

It is a super-2 number, since 2×21030013² = 884522893560338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030043) 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, 36873 + ... + 37438.

It is an arithmetic number, because the mean of its divisors is an integer number (5276152).

Almost surely, 2^21030013 is an apocalyptic number.

It is an amenable number.

21030013 is a deficient number, since it is larger than the sum of its proper divisors (74595).

21030013 is an equidigital number, since it uses as much as digits as its factorization.

21030013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74594.

The product of its (nonzero) digits is 18, while the sum is 10.

The square root of 21030013 is about 4585.8492125232. The cubic root of 21030013 is about 276.0237893448.

Adding to 21030013 its reverse (31003012), we get a palindrome (52033025).

The spelling of 21030013 in words is "twenty-one million, thirty thousand, thirteen".