21020244131 has 4 divisors (see below), whose sum is σ = 21022553832. Its totient is φ = 21017934432.

The previous prime is 21020244109. The next prime is 21020244169. The reversal of 21020244131 is 13144202012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21020244131 - 2¹⁰ = 21020243107 is a prime.

It is a super-2 number, since 2×21020244131² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020244181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1141145 + ... + 1159418.

It is an arithmetic number, because the mean of its divisors is an integer number (5255638458).

Almost surely, 2^21020244131 is an apocalyptic number.

21020244131 is a deficient number, since it is larger than the sum of its proper divisors (2309701).

21020244131 is an equidigital number, since it uses as much as digits as its factorization.

21020244131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2309700.

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21020244131 its reverse (13144202012), we get a palindrome (34164446143).

The spelling of 21020244131 in words is "twenty-one billion, twenty million, two hundred forty-four thousand, one hundred thirty-one".