639744401806 has 16 divisors (see below), whose sum is σ = 987747231600. Its totient is φ = 310533834240.

The previous prime is 639744401771. The next prime is 639744401809. The reversal of 639744401806 is 608104447936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639744401809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9593940 + ... + 9660391.

It is an arithmetic number, because the mean of its divisors is an integer number (61734201975).

Almost surely, 2^639744401806 is an apocalyptic number.

639744401806 is a deficient number, since it is larger than the sum of its proper divisors (348002829794).

639744401806 is a wasteful number, since it uses less digits than its factorization.

639744401806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19254819.

The product of its (nonzero) digits is 3483648, while the sum is 52.

The spelling of 639744401806 in words is "six hundred thirty-nine billion, seven hundred forty-four million, four hundred one thousand, eight hundred six".