21021020210257 has 2 divisors, whose sum is σ = 21021020210258. Its totient is φ = 21021020210256.

The previous prime is 21021020210227. The next prime is 21021020210347. The reversal of 21021020210257 is 75201202012012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20945716069201 + 75304141056 = 4576649^2 + 274416^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021020210257 - 2⁷ = 21021020210129 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021020210227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510510105128 + 10510510105129.

It is an arithmetic number, because the mean of its divisors is an integer number (10510510105129).

Almost surely, 2^{21021020210257} is an apocalyptic number.

It is an amenable number.

21021020210257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021020210257 is an equidigital number, since it uses as much as digits as its factorization.

21021020210257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1120, while the sum is 25.

Adding to 21021020210257 its reverse (75201202012012), we get a palindrome (96222222222269).

The spelling of 21021020210257 in words is "twenty-one trillion, twenty-one billion, twenty million, two hundred ten thousand, two hundred fifty-seven".