642220817857 has 2 divisors, whose sum is σ = 642220817858. Its totient is φ = 642220817856.

The previous prime is 642220817807. The next prime is 642220817897. The reversal of 642220817857 is 758718022246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 544704517681 + 97516300176 = 738041^2 + 312276^2 .

It is a cyclic number.

It is not a de Polignac number, because 642220817857 - 2¹¹ = 642220815809 is a prime.

It is not a weakly prime, because it can be changed into another prime (642220817807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321110408928 + 321110408929.

It is an arithmetic number, because the mean of its divisors is an integer number (321110408929).

Almost surely, 2^642220817857 is an apocalyptic number.

It is an amenable number.

642220817857 is a deficient number, since it is larger than the sum of its proper divisors (1).

642220817857 is an equidigital number, since it uses as much as digits as its factorization.

642220817857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3010560, while the sum is 52.

The spelling of 642220817857 in words is "six hundred forty-two billion, two hundred twenty million, eight hundred seventeen thousand, eight hundred fifty-seven".