642868247 has 4 divisors (see below), whose sum is σ = 734706576. Its totient is φ = 551029920.

The previous prime is 642868231. The next prime is 642868273. The reversal of 642868247 is 742868246.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 642868247 - 2⁴ = 642868231 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642868207) 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 in 3 ways as a sum of consecutive naturals, for example, 45919154 + ... + 45919167.

It is an arithmetic number, because the mean of its divisors is an integer number (183676644).

Almost surely, 2^642868247 is an apocalyptic number.

642868247 is a deficient number, since it is larger than the sum of its proper divisors (91838329).

642868247 is an equidigital number, since it uses as much as digits as its factorization.

642868247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91838328.

The product of its digits is 1032192, while the sum is 47.

The square root of 642868247 is about 25354.8466175601. The cubic root of 642868247 is about 863.0593431799.

Subtracting 642868247 from its reverse (742868246), we obtain a palindrome (99999999).

The spelling of 642868247 in words is "six hundred forty-two million, eight hundred sixty-eight thousand, two hundred forty-seven".