639861841 has 4 divisors (see below), whose sum is σ = 673538800. Its totient is φ = 606184884.

The previous prime is 639861839. The next prime is 639861883. The reversal of 639861841 is 148168936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 639861841 - 2¹ = 639861839 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 639861791 and 639861800.

It is not an unprimeable number, because it can be changed into a prime (639841841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16838451 + ... + 16838488.

It is an arithmetic number, because the mean of its divisors is an integer number (168384700).

Almost surely, 2^639861841 is an apocalyptic number.

It is an amenable number.

639861841 is a deficient number, since it is larger than the sum of its proper divisors (33676959).

639861841 is a wasteful number, since it uses less digits than its factorization.

639861841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33676958.

The product of its digits is 248832, while the sum is 46.

The square root of 639861841 is about 25295.4905269694. The cubic root of 639861841 is about 861.7118601870.

The spelling of 639861841 in words is "six hundred thirty-nine million, eight hundred sixty-one thousand, eight hundred forty-one".