642797 has 2 divisors, whose sum is σ = 642798. Its totient is φ = 642796.

The previous prime is 642791. The next prime is 642799. The reversal of 642797 is 797246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 561001 + 81796 = 749^2 + 286^2 .

642797 is a truncatable prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642797 is a prime.

Together with 642799, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321398 + 321399.

It is an arithmetic number, because the mean of its divisors is an integer number (321399).

2⁶⁴²⁷⁹⁷ is an apocalyptic number.

It is an amenable number.

642797 is a deficient number, since it is larger than the sum of its proper divisors (1).

642797 is an equidigital number, since it uses as much as digits as its factorization.

642797 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21168, while the sum is 35.

The square root of 642797 is about 801.7462191991. The cubic root of 642797 is about 86.3027458647.

Subtracting 642797 from its reverse (797246), we obtain a square (154449 = 393²).

The spelling of 642797 in words is "six hundred forty-two thousand, seven hundred ninety-seven".