21111221207 has 2 divisors, whose sum is σ = 21111221208. Its totient is φ = 21111221206.

The previous prime is 21111221167. The next prime is 21111221213. The reversal of 21111221207 is 70212211112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21111221207 - 2⁶ = 21111221143 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111221227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555610603 + 10555610604.

It is an arithmetic number, because the mean of its divisors is an integer number (10555610604).

Almost surely, 2^21111221207 is an apocalyptic number.

21111221207 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111221207 is an equidigital number, since it uses as much as digits as its factorization.

21111221207 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112, while the sum is 20.

Adding to 21111221207 its reverse (70212211112), we get a palindrome (91323432319).

The spelling of 21111221207 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, two hundred seven".