21001011122257 has 2 divisors, whose sum is σ = 21001011122258. Its totient is φ = 21001011122256.

The previous prime is 21001011122153. The next prime is 21001011122263. The reversal of 21001011122257 is 75222111010012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20752798914576 + 248212207681 = 4555524^2 + 498209^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001011122257 - 2³⁹ = 20451255308369 is a prime.

It is a super-3 number, since 3×21001011122257³ (a number of 41 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21001011122857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500505561128 + 10500505561129.

It is an arithmetic number, because the mean of its divisors is an integer number (10500505561129).

Almost surely, 2^{21001011122257} is an apocalyptic number.

It is an amenable number.

21001011122257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001011122257 is an equidigital number, since it uses as much as digits as its factorization.

21001011122257 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 25.

Adding to 21001011122257 its reverse (75222111010012), we get a palindrome (96223122132269).

The spelling of 21001011122257 in words is "twenty-one trillion, one billion, eleven million, one hundred twenty-two thousand, two hundred fifty-seven".