21000020113 has 4 divisors (see below), whose sum is σ = 21034056420. Its totient is φ = 20965983808.

The previous prime is 21000020057. The next prime is 21000020137. The reversal of 21000020113 is 31102000012.

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 3642484609 + 17357535504 = 60353^2 + 131748^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21000020113 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 21000020113.

It is not an unprimeable number, because it can be changed into a prime (21000020413) 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, 17017228 + ... + 17018461.

It is an arithmetic number, because the mean of its divisors is an integer number (5258514105).

Almost surely, 2^21000020113 is an apocalyptic number.

It is an amenable number.

21000020113 is a deficient number, since it is larger than the sum of its proper divisors (34036307).

21000020113 is an equidigital number, since it uses as much as digits as its factorization.

21000020113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34036306.

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

Adding to 21000020113 its reverse (31102000012), we get a palindrome (52102020125).

The spelling of 21000020113 in words is "twenty-one billion, twenty thousand, one hundred thirteen".