20421100019857 has 2 divisors, whose sum is σ = 20421100019858. Its totient is φ = 20421100019856.

The previous prime is 20421100019843. The next prime is 20421100019941. The reversal of 20421100019857 is 75891000112402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14547694452736 + 5873405567121 = 3814144^2 + 2423511^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421100019857 - 2¹¹ = 20421100017809 is a prime.

It is not a weakly prime, because it can be changed into another prime (20421100013857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210550009928 + 10210550009929.

It is an arithmetic number, because the mean of its divisors is an integer number (10210550009929).

Almost surely, 2^{20421100019857} is an apocalyptic number.

It is an amenable number.

20421100019857 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421100019857 is an equidigital number, since it uses as much as digits as its factorization.

20421100019857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 40.

The spelling of 20421100019857 in words is "twenty trillion, four hundred twenty-one billion, one hundred million, nineteen thousand, eight hundred fifty-seven".