21020120311 has 4 divisors (see below), whose sum is σ = 21074157000. Its totient is φ = 20966083624.

The previous prime is 21020120243. The next prime is 21020120327. The reversal of 21020120311 is 11302102012.

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 21020120311 - 2¹¹ = 21020118263 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020120291 and 21020120300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020120111) 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, 27017761 + ... + 27018538.

It is an arithmetic number, because the mean of its divisors is an integer number (5268539250).

Almost surely, 2^21020120311 is an apocalyptic number.

21020120311 is a deficient number, since it is larger than the sum of its proper divisors (54036689).

21020120311 is an equidigital number, since it uses as much as digits as its factorization.

21020120311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54036688.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21020120311 its reverse (11302102012), we get a palindrome (32322222323).

The spelling of 21020120311 in words is "twenty-one billion, twenty million, one hundred twenty thousand, three hundred eleven".