21020113 has 4 divisors (see below), whose sum is σ = 21092148. Its totient is φ = 20948080.

The previous prime is 21020093. The next prime is 21020117. The reversal of 21020113 is 31102012.

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 17205904 + 3814209 = 4148^2 + 1953^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020113 - 2⁵ = 21020081 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 21020113.

It is not an unprimeable number, because it can be changed into a prime (21020117) 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, 35578 + ... + 36163.

It is an arithmetic number, because the mean of its divisors is an integer number (5273037).

Almost surely, 2^21020113 is an apocalyptic number.

It is an amenable number.

21020113 is a deficient number, since it is larger than the sum of its proper divisors (72035).

21020113 is an equidigital number, since it uses as much as digits as its factorization.

21020113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72034.

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

The square root of 21020113 is about 4584.7696779664. The cubic root of 21020113 is about 275.9804692824.

Adding to 21020113 its reverse (31102012), we get a palindrome (52122125).

The spelling of 21020113 in words is "twenty-one million, twenty thousand, one hundred thirteen".