21021012013 has 4 divisors (see below), whose sum is σ = 21021318108. Its totient is φ = 21020705920.

The previous prime is 21021011993. The next prime is 21021012029. The reversal of 21021012013 is 31021012012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 11580557769 + 9440454244 = 107613^2 + 97162^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021012013 - 2²⁹ = 20484141101 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021011984 and 21021012002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021010013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3003 + ... + 205063.

It is an arithmetic number, because the mean of its divisors is an integer number (5255329527).

Almost surely, 2^21021012013 is an apocalyptic number.

It is an amenable number.

21021012013 is a deficient number, since it is larger than the sum of its proper divisors (306095).

21021012013 is a wasteful number, since it uses less digits than its factorization.

21021012013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306094.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21021012013 its reverse (31021012012), we get a palindrome (52042024025).

Subtracting 21021012013 from its reverse (31021012012), we obtain a palindrome (9999999999).

The spelling of 21021012013 in words is "twenty-one billion, twenty-one million, twelve thousand, thirteen".