21001200122257 has 2 divisors, whose sum is σ = 21001200122258. Its totient is φ = 21001200122256.

The previous prime is 21001200122171. The next prime is 21001200122267. The reversal of 21001200122257 is 75222100210012.

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., 20108847835521 + 892352286736 = 4484289^2 + 944644^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001200122257 - 2¹¹ = 21001200120209 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001200122267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500600061128 + 10500600061129.

It is an arithmetic number, because the mean of its divisors is an integer number (10500600061129).

Almost surely, 2^{21001200122257} is an apocalyptic number.

It is an amenable number.

21001200122257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001200122257 is an equidigital number, since it uses as much as digits as its factorization.

21001200122257 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21001200122257 its reverse (75222100210012), we get a palindrome (96223300332269).

The spelling of 21001200122257 in words is "twenty-one trillion, one billion, two hundred million, one hundred twenty-two thousand, two hundred fifty-seven".