642421236641 has 2 divisors, whose sum is σ = 642421236642. Its totient is φ = 642421236640.

The previous prime is 642421236623. The next prime is 642421236679. The reversal of 642421236641 is 146632124246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 482358030400 + 160063206241 = 694520^2 + 400079^2 .

It is a cyclic number.

It is not a de Polignac number, because 642421236641 - 2¹⁴ = 642421220257 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (642421226641) 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, 321210618320 + 321210618321.

It is an arithmetic number, because the mean of its divisors is an integer number (321210618321).

Almost surely, 2^642421236641 is an apocalyptic number.

It is an amenable number.

642421236641 is a deficient number, since it is larger than the sum of its proper divisors (1).

642421236641 is an equidigital number, since it uses as much as digits as its factorization.

642421236641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 331776, while the sum is 41.

The spelling of 642421236641 in words is "six hundred forty-two billion, four hundred twenty-one million, two hundred thirty-six thousand, six hundred forty-one".