639880379781 has 8 divisors (see below), whose sum is σ = 853183654464. Its totient is φ = 426582012480.

The previous prime is 639880379773. The next prime is 639880379791. The reversal of 639880379781 is 187973088936.

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

It is not a de Polignac number, because 639880379781 - 2³ = 639880379773 is a prime.

It is a super-2 number, since 2×639880379781² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639880379791) 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, 910980 + ... + 1452461.

It is an arithmetic number, because the mean of its divisors is an integer number (106647956808).

Almost surely, 2^639880379781 is an apocalyptic number.

It is an amenable number.

639880379781 is a deficient number, since it is larger than the sum of its proper divisors (213303274683).

639880379781 is a wasteful number, since it uses less digits than its factorization.

639880379781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2453691.

The product of its (nonzero) digits is 109734912, while the sum is 69.

The spelling of 639880379781 in words is "six hundred thirty-nine billion, eight hundred eighty million, three hundred seventy-nine thousand, seven hundred eighty-one".