642505247 has 2 divisors, whose sum is σ = 642505248. Its totient is φ = 642505246.

The previous prime is 642505229. The next prime is 642505249. The reversal of 642505247 is 742505246.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642505247 - 2¹⁴ = 642488863 is a prime.

Together with 642505249, 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 (642505249) 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, 321252623 + 321252624.

It is an arithmetic number, because the mean of its divisors is an integer number (321252624).

Almost surely, 2^642505247 is an apocalyptic number.

642505247 is a deficient number, since it is larger than the sum of its proper divisors (1).

642505247 is an equidigital number, since it uses as much as digits as its factorization.

642505247 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 67200, while the sum is 35.

The square root of 642505247 is about 25347.6872120515. The cubic root of 642505247 is about 862.8968684537.

Subtracting 642505247 from its reverse (742505246), we obtain a palindrome (99999999).

The spelling of 642505247 in words is "six hundred forty-two million, five hundred five thousand, two hundred forty-seven".