21200121011 has 2 divisors, whose sum is σ = 21200121012. Its totient is φ = 21200121010.

The previous prime is 21200120989. The next prime is 21200121013. The reversal of 21200121011 is 11012100212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21200121011 is a prime.

Together with 21200121013, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21200120983 and 21200121001.

It is not a weakly prime, because it can be changed into another prime (21200121013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600060505 + 10600060506.

It is an arithmetic number, because the mean of its divisors is an integer number (10600060506).

Almost surely, 2^21200121011 is an apocalyptic number.

21200121011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21200121011 is an equidigital number, since it uses as much as digits as its factorization.

21200121011 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21200121011 its reverse (11012100212), we get a palindrome (32212221223).

The spelling of 21200121011 in words is "twenty-one billion, two hundred million, one hundred twenty-one thousand, eleven".