102111202120021 has 2 divisors, whose sum is σ = 102111202120022. Its totient is φ = 102111202120020.

The previous prime is 102111202120019. The next prime is 102111202120033. The reversal of 102111202120021 is 120021202111201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 96244929202500 + 5866272917521 = 9810450^2 + 2422039^2 .

It is an emirp because it is prime and its reverse (120021202111201) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 102111202120021 - 2¹ = 102111202120019 is a prime.

Together with 102111202120019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 102111202119977 and 102111202120004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (102111202120051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51055601060010 + 51055601060011.

It is an arithmetic number, because the mean of its divisors is an integer number (51055601060011).

Almost surely, 2^{102111202120021} is an apocalyptic number.

It is an amenable number.

102111202120021 is a deficient number, since it is larger than the sum of its proper divisors (1).

102111202120021 is an equidigital number, since it uses as much as digits as its factorization.

102111202120021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 102111202120021 its reverse (120021202111201), we get a palindrome (222132404231222).

The spelling of 102111202120021 in words is "one hundred two trillion, one hundred eleven billion, two hundred two million, one hundred twenty thousand, twenty-one".