21000212220257 has 2 divisors, whose sum is σ = 21000212220258. Its totient is φ = 21000212220256.

The previous prime is 21000212220193. The next prime is 21000212220271. The reversal of 21000212220257 is 75202221200012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17640033600016 + 3360178620241 = 4200004^2 + 1833079^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000212220257 - 2⁶ = 21000212220193 is a prime.

It is a super-2 number, since 2×21000212220257² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21000212220857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500106110128 + 10500106110129.

It is an arithmetic number, because the mean of its divisors is an integer number (10500106110129).

Almost surely, 2^{21000212220257} is an apocalyptic number.

It is an amenable number.

21000212220257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000212220257 is an equidigital number, since it uses as much as digits as its factorization.

21000212220257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 26.

Adding to 21000212220257 its reverse (75202221200012), we get a palindrome (96202433420269).

The spelling of 21000212220257 in words is "twenty-one trillion, two hundred twelve million, two hundred twenty thousand, two hundred fifty-seven".