21000012211121 has 2 divisors, whose sum is σ = 21000012211122. Its totient is φ = 21000012211120.

The previous prime is 21000012211111. The next prime is 21000012211127. The reversal of 21000012211121 is 12111221000012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16658356546225 + 4341655664896 = 4081465^2 + 2083664^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000012211121 - 2⁴² = 16601965700017 is a prime.

It is a super-2 number, since 2×21000012211121² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21000012211096 and 21000012211105.

It is not a weakly prime, because it can be changed into another prime (21000012211127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500006105560 + 10500006105561.

It is an arithmetic number, because the mean of its divisors is an integer number (10500006105561).

Almost surely, 2^{21000012211121} is an apocalyptic number.

It is an amenable number.

21000012211121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000012211121 is an equidigital number, since it uses as much as digits as its factorization.

21000012211121 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 14.

Adding to 21000012211121 its reverse (12111221000012), we get a palindrome (33111233211133).

The spelling of 21000012211121 in words is "twenty-one trillion, twelve million, two hundred eleven thousand, one hundred twenty-one".