642642636869 has 2 divisors, whose sum is σ = 642642636870. Its totient is φ = 642642636868.

The previous prime is 642642636859. The next prime is 642642636907. The reversal of 642642636869 is 968636246246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 406072268644 + 236570368225 = 637238^2 + 486385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642642636869 is a prime.

It is a super-2 number, since 2×642642636869² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642642636859) 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, 321321318434 + 321321318435.

It is an arithmetic number, because the mean of its divisors is an integer number (321321318435).

Almost surely, 2^642642636869 is an apocalyptic number.

It is an amenable number.

642642636869 is a deficient number, since it is larger than the sum of its proper divisors (1).

642642636869 is an equidigital number, since it uses as much as digits as its factorization.

642642636869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 107495424, while the sum is 62.

The spelling of 642642636869 in words is "six hundred forty-two billion, six hundred forty-two million, six hundred thirty-six thousand, eight hundred sixty-nine".