21015020121313 has 4 divisors (see below), whose sum is σ = 21015043033348. Its totient is φ = 21014997209280.

The previous prime is 21015020121307. The next prime is 21015020121317. The reversal of 21015020121313 is 31312102051012.

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 10771839074304 + 10243181047009 = 3282048^2 + 3200497^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21015020121313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21015020121317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10020228 + ... + 11934613.

It is an arithmetic number, because the mean of its divisors is an integer number (5253760758337).

Almost surely, 2^{21015020121313} is an apocalyptic number.

It is an amenable number.

21015020121313 is a deficient number, since it is larger than the sum of its proper divisors (22912035).

21015020121313 is an equidigital number, since it uses as much as digits as its factorization.

21015020121313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22912034.

The product of its (nonzero) digits is 360, while the sum is 22.

Adding to 21015020121313 its reverse (31312102051012), we get a palindrome (52327122172325).

The spelling of 21015020121313 in words is "twenty-one trillion, fifteen billion, twenty million, one hundred twenty-one thousand, three hundred thirteen".