21020204131 has 4 divisors (see below), whose sum is σ = 21698275264. Its totient is φ = 20342133000.

The previous prime is 21020204129. The next prime is 21020204201. The reversal of 21020204131 is 13140202012.

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 21020204131 - 2¹ = 21020204129 is a prime.

It is a super-2 number, since 2×21020204131² (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 (21020204111) 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, 339035520 + ... + 339035581.

It is an arithmetic number, because the mean of its divisors is an integer number (5424568816).

Almost surely, 2^21020204131 is an apocalyptic number.

21020204131 is a deficient number, since it is larger than the sum of its proper divisors (678071133).

21020204131 is an equidigital number, since it uses as much as digits as its factorization.

21020204131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 678071132.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21020204131 its reverse (13140202012), we get a palindrome (34160406143).

The spelling of 21020204131 in words is "twenty-one billion, twenty million, two hundred four thousand, one hundred thirty-one".