212817856204781 has 2 divisors, whose sum is σ = 212817856204782. Its totient is φ = 212817856204780.

The previous prime is 212817856204727. The next prime is 212817856204823. The reversal of 212817856204781 is 187402658718212.

212817856204781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138279584266756 + 74538271938025 = 11759234^2 + 8633555^2 .

It is a cyclic number.

It is not a de Polignac number, because 212817856204781 - 2³⁰ = 212816782462957 is a prime.

It is a super-2 number, since 2×212817856204781² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212817856209781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106408928102390 + 106408928102391.

It is an arithmetic number, because the mean of its divisors is an integer number (106408928102391).

Almost surely, 2^{212817856204781} is an apocalyptic number.

It is an amenable number.

212817856204781 is a deficient number, since it is larger than the sum of its proper divisors (1).

212817856204781 is an equidigital number, since it uses as much as digits as its factorization.

212817856204781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24084480, while the sum is 62.

The spelling of 212817856204781 in words is "two hundred twelve trillion, eight hundred seventeen billion, eight hundred fifty-six million, two hundred four thousand, seven hundred eighty-one".