642847679 has 2 divisors, whose sum is σ = 642847680. Its totient is φ = 642847678.

The previous prime is 642847663. The next prime is 642847697. The reversal of 642847679 is 976748246.

Together with next prime (642847697) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 642847679 - 2⁴ = 642847663 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642847679.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642844679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321423839 + 321423840.

It is an arithmetic number, because the mean of its divisors is an integer number (321423840).

Almost surely, 2^642847679 is an apocalyptic number.

642847679 is a deficient number, since it is larger than the sum of its proper divisors (1).

642847679 is an equidigital number, since it uses as much as digits as its factorization.

642847679 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4064256, while the sum is 53.

The square root of 642847679 is about 25354.4410113889. The cubic root of 642847679 is about 863.0501388088.

The spelling of 642847679 in words is "six hundred forty-two million, eight hundred forty-seven thousand, six hundred seventy-nine".