21002212121257 has 2 divisors, whose sum is σ = 21002212121258. Its totient is φ = 21002212121256.

The previous prime is 21002212121227. The next prime is 21002212121279. The reversal of 21002212121257 is 75212121220012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20983032364176 + 19179757081 = 4580724^2 + 138491^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002212121257 - 2¹⁹ = 21002211596969 is a prime.

It is not a weakly prime, because it can be changed into another prime (21002212121227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501106060628 + 10501106060629.

It is an arithmetic number, because the mean of its divisors is an integer number (10501106060629).

Almost surely, 2^{21002212121257} is an apocalyptic number.

It is an amenable number.

21002212121257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002212121257 is an equidigital number, since it uses as much as digits as its factorization.

21002212121257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2240, while the sum is 28.

Adding to 21002212121257 its reverse (75212121220012), we get a palindrome (96214333341269).

The spelling of 21002212121257 in words is "twenty-one trillion, two billion, two hundred twelve million, one hundred twenty-one thousand, two hundred fifty-seven".