639842977 has 8 divisors (see below), whose sum is σ = 652725864. Its totient is φ = 626990208.

The previous prime is 639842963. The next prime is 639843011. The reversal of 639842977 is 779248936.

It can be written as a sum of positive squares in 4 ways, for example, as 19633761 + 620209216 = 4431^2 + 24904^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 639842977 - 2¹⁹ = 639318689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639842927) 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 7 ways as a sum of consecutive naturals, for example, 38133 + ... + 52285.

It is an arithmetic number, because the mean of its divisors is an integer number (81590733).

Almost surely, 2^639842977 is an apocalyptic number.

It is an amenable number.

639842977 is a deficient number, since it is larger than the sum of its proper divisors (12882887).

639842977 is a wasteful number, since it uses less digits than its factorization.

639842977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15059.

The product of its digits is 4572288, while the sum is 55.

The square root of 639842977 is about 25295.1176514362. The cubic root of 639842977 is about 861.7033919567.

The spelling of 639842977 in words is "six hundred thirty-nine million, eight hundred forty-two thousand, nine hundred seventy-seven".