642805906997 has 2 divisors, whose sum is σ = 642805906998. Its totient is φ = 642805906996.

The previous prime is 642805906961. The next prime is 642805907027. The reversal of 642805906997 is 799609508246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 642804666001 + 1240996 = 801751^2 + 1114^2 .

It is a cyclic number.

It is not a de Polignac number, because 642805906997 - 2¹² = 642805902901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642805906957) 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, 321402953498 + 321402953499.

It is an arithmetic number, because the mean of its divisors is an integer number (321402953499).

Almost surely, 2^642805906997 is an apocalyptic number.

It is an amenable number.

642805906997 is a deficient number, since it is larger than the sum of its proper divisors (1).

642805906997 is an equidigital number, since it uses as much as digits as its factorization.

642805906997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 58786560, while the sum is 65.

The spelling of 642805906997 in words is "six hundred forty-two billion, eight hundred five million, nine hundred six thousand, nine hundred ninety-seven".