21100121212057 has 2 divisors, whose sum is σ = 21100121212058. Its totient is φ = 21100121212056.

The previous prime is 21100121212021. The next prime is 21100121212139. The reversal of 21100121212057 is 75021212100112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20711018476096 + 389102735961 = 4550936^2 + 623781^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100121212057 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100121212007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550060606028 + 10550060606029.

It is an arithmetic number, because the mean of its divisors is an integer number (10550060606029).

Almost surely, 2^{21100121212057} is an apocalyptic number.

It is an amenable number.

21100121212057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100121212057 is an equidigital number, since it uses as much as digits as its factorization.

21100121212057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 560, while the sum is 25.

Adding to 21100121212057 its reverse (75021212100112), we get a palindrome (96121333312169).

The spelling of 21100121212057 in words is "twenty-one trillion, one hundred billion, one hundred twenty-one million, two hundred twelve thousand, fifty-seven".