639918036739 has 4 divisors (see below), whose sum is σ = 640082586280. Its totient is φ = 639753487200.

The previous prime is 639918036689. The next prime is 639918036761. The reversal of 639918036739 is 937630819936.

639918036739 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 639918036739 - 2²¹ = 639915939587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639918036239) 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, 82268937 + ... + 82276714.

It is an arithmetic number, because the mean of its divisors is an integer number (160020646570).

Almost surely, 2^639918036739 is an apocalyptic number.

639918036739 is a deficient number, since it is larger than the sum of its proper divisors (164549541).

639918036739 is a wasteful number, since it uses less digits than its factorization.

639918036739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164549540.

The product of its (nonzero) digits is 39680928, while the sum is 64.

The spelling of 639918036739 in words is "six hundred thirty-nine billion, nine hundred eighteen million, thirty-six thousand, seven hundred thirty-nine".