639542719 has 4 divisors (see below), whose sum is σ = 639676296. Its totient is φ = 639409144.

The previous prime is 639542711. The next prime is 639542747. The reversal of 639542719 is 917245936.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 639542719 - 2³ = 639542711 is a prime.

It is a super-2 number, since 2×639542719² = 818029778851825922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639542711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59329 + ... + 69274.

It is an arithmetic number, because the mean of its divisors is an integer number (159919074).

Almost surely, 2^639542719 is an apocalyptic number.

639542719 is a deficient number, since it is larger than the sum of its proper divisors (133577).

639542719 is a wasteful number, since it uses less digits than its factorization.

639542719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133576.

The product of its digits is 408240, while the sum is 46.

The square root of 639542719 is about 25289.1818570708. The cubic root of 639542719 is about 861.5685808501.

The spelling of 639542719 in words is "six hundred thirty-nine million, five hundred forty-two thousand, seven hundred nineteen".