20311211021 has 4 divisors (see below), whose sum is σ = 20312848032. Its totient is φ = 20309574012.

The previous prime is 20311211017. The next prime is 20311211027. The reversal of 20311211021 is 12011211302.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12011211302 = 2 ⋅6005605651.

It is a cyclic number.

It is not a de Polignac number, because 20311211021 - 2² = 20311211017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20311210987 and 20311211005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20311211027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 799751 + ... + 824756.

It is an arithmetic number, because the mean of its divisors is an integer number (5078212008).

Almost surely, 2^20311211021 is an apocalyptic number.

It is an amenable number.

20311211021 is a deficient number, since it is larger than the sum of its proper divisors (1637011).

20311211021 is a wasteful number, since it uses less digits than its factorization.

20311211021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1637010.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 20311211021 its reverse (12011211302), we get a palindrome (32322422323).

The spelling of 20311211021 in words is "twenty billion, three hundred eleven million, two hundred eleven thousand, twenty-one".