21131012005 has 4 divisors (see below), whose sum is σ = 25357214412. Its totient is φ = 16904809600.

The previous prime is 21131011999. The next prime is 21131012009. The reversal of 21131012005 is 50021013112.

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 9362884644 + 11768127361 = 96762^2 + 108481^2 .

It is not a de Polignac number, because 21131012005 - 2⁹ = 21131011493 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 21131012005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131012009) 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, 2113101196 + ... + 2113101205.

It is an arithmetic number, because the mean of its divisors is an integer number (6339303603).

Almost surely, 2^21131012005 is an apocalyptic number.

It is an amenable number.

21131012005 is a deficient number, since it is larger than the sum of its proper divisors (4226202407).

21131012005 is an equidigital number, since it uses as much as digits as its factorization.

21131012005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4226202406.

The product of its (nonzero) digits is 60, while the sum is 16.

Adding to 21131012005 its reverse (50021013112), we get a palindrome (71152025117).

The spelling of 21131012005 in words is "twenty-one billion, one hundred thirty-one million, twelve thousand, five".