639925423 has 2 divisors, whose sum is σ = 639925424. Its totient is φ = 639925422.

The previous prime is 639925421. The next prime is 639925457. The reversal of 639925423 is 324529936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639925423 - 2¹ = 639925421 is a prime.

Together with 639925421, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 639925423.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639925421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319962711 + 319962712.

It is an arithmetic number, because the mean of its divisors is an integer number (319962712).

Almost surely, 2^639925423 is an apocalyptic number.

639925423 is a deficient number, since it is larger than the sum of its proper divisors (1).

639925423 is an equidigital number, since it uses as much as digits as its factorization.

639925423 is an evil number, because the sum of its binary digits is even.

The product of its digits is 349920, while the sum is 43.

The square root of 639925423 is about 25296.7472810241. The cubic root of 639925423 is about 861.7404015300.

The spelling of 639925423 in words is "six hundred thirty-nine million, nine hundred twenty-five thousand, four hundred twenty-three".