20011311821 has 2 divisors, whose sum is σ = 20011311822. Its totient is φ = 20011311820.

The previous prime is 20011311799. The next prime is 20011311833. The reversal of 20011311821 is 12811311002.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19996788100 + 14523721 = 141410^2 + 3811^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20011311821 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20011311793 and 20011311802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20011311121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10005655910 + 10005655911.

It is an arithmetic number, because the mean of its divisors is an integer number (10005655911).

Almost surely, 2^20011311821 is an apocalyptic number.

It is an amenable number.

20011311821 is a deficient number, since it is larger than the sum of its proper divisors (1).

20011311821 is an equidigital number, since it uses as much as digits as its factorization.

20011311821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 20.

Adding to 20011311821 its reverse (12811311002), we get a palindrome (32822622823).

The spelling of 20011311821 in words is "twenty billion, eleven million, three hundred eleven thousand, eight hundred twenty-one".