642516439 has 2 divisors, whose sum is σ = 642516440. Its totient is φ = 642516438.

The previous prime is 642516421. The next prime is 642516451. The reversal of 642516439 is 934615246.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642516439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642516239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321258219 + 321258220.

It is an arithmetic number, because the mean of its divisors is an integer number (321258220).

Almost surely, 2^642516439 is an apocalyptic number.

642516439 is a deficient number, since it is larger than the sum of its proper divisors (1).

642516439 is an equidigital number, since it uses as much as digits as its factorization.

642516439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 40.

The square root of 642516439 is about 25347.9079807388. The cubic root of 642516439 is about 862.9018787815.

The spelling of 642516439 in words is "six hundred forty-two million, five hundred sixteen thousand, four hundred thirty-nine".