20121223021 has 2 divisors, whose sum is σ = 20121223022. Its totient is φ = 20121223020.

The previous prime is 20121223013. The next prime is 20121223039. The reversal of 20121223021 is 12032212102.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10993522500 + 9127700521 = 104850^2 + 95539^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121223021 - 2³ = 20121223013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20121222986 and 20121223004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20121223051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060611510 + 10060611511.

It is an arithmetic number, because the mean of its divisors is an integer number (10060611511).

Almost surely, 2^20121223021 is an apocalyptic number.

It is an amenable number.

20121223021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121223021 is an equidigital number, since it uses as much as digits as its factorization.

20121223021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 20121223021 its reverse (12032212102), we get a palindrome (32153435123).

The spelling of 20121223021 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-three thousand, twenty-one".