21010212257 has 2 divisors, whose sum is σ = 21010212258. Its totient is φ = 21010212256.

The previous prime is 21010212199. The next prime is 21010212259. The reversal of 21010212257 is 75221201012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19388056081 + 1622156176 = 139241^2 + 40276^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010212257 - 2⁶ = 21010212193 is a prime.

Together with 21010212259, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21010212259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505106128 + 10505106129.

It is an arithmetic number, because the mean of its divisors is an integer number (10505106129).

Almost surely, 2^21010212257 is an apocalyptic number.

It is an amenable number.

21010212257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010212257 is an equidigital number, since it uses as much as digits as its factorization.

21010212257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 560, while the sum is 23.

Adding to 21010212257 its reverse (75221201012), we get a palindrome (96231413269).

The spelling of 21010212257 in words is "twenty-one billion, ten million, two hundred twelve thousand, two hundred fifty-seven".