21020131311 has 4 divisors (see below), whose sum is σ = 28026841752. Its totient is φ = 14013420872.

The previous prime is 21020131271. The next prime is 21020131331. The reversal of 21020131311 is 11313102012.

It is a happy number.

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 21020131311 - 2⁹ = 21020130799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020131331) 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, 3503355216 + ... + 3503355221.

It is an arithmetic number, because the mean of its divisors is an integer number (7006710438).

Almost surely, 2^21020131311 is an apocalyptic number.

21020131311 is a deficient number, since it is larger than the sum of its proper divisors (7006710441).

21020131311 is an equidigital number, since it uses as much as digits as its factorization.

21020131311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7006710440.

The product of its (nonzero) digits is 36, while the sum is 15.

Adding to 21020131311 its reverse (11313102012), we get a palindrome (32333233323).

The spelling of 21020131311 in words is "twenty-one billion, twenty million, one hundred thirty-one thousand, three hundred eleven".