20121211021 has 2 divisors, whose sum is σ = 20121211022. Its totient is φ = 20121211020.

The previous prime is 20121211001. The next prime is 20121211037. The reversal of 20121211021 is 12011212102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18059596996 + 2061614025 = 134386^2 + 45405^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121211021 - 2²¹ = 20119113869 is a prime.

It is a super-2 number, since 2×20121211021² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20121210992 and 20121211010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20121211001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060605510 + 10060605511.

It is an arithmetic number, because the mean of its divisors is an integer number (10060605511).

Almost surely, 2^20121211021 is an apocalyptic number.

It is an amenable number.

20121211021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121211021 is an equidigital number, since it uses as much as digits as its factorization.

20121211021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 20121211021 its reverse (12011212102), we get a palindrome (32132423123).

The spelling of 20121211021 in words is "twenty billion, one hundred twenty-one million, two hundred eleven thousand, twenty-one".