639765967680 has 1176 divisors, whose sum is σ = 2689081117128. Its totient is φ = 144473849856.

The previous prime is 639765967661. The next prime is 639765967699. The reversal of 639765967680 is 86769567936.

639765967680 is a `hidden beast` number, since 6 + 397 + 6 + 5 + 96 + 76 + 80 = 666.

It is an interprime number because it is at equal distance from previous prime (639765967661) and next prime (639765967699).

It can be written as a sum of positive squares in 4 ways, for example, as 232640299584 + 407125668096 = 482328^2 + 638064^2 .

It is a tau number, because it is divible by the number of its divisors (1176).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 639765967599 and 639765967608.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 167 ways as a sum of consecutive naturals, for example, 1108779552 + ... + 1108780128.

It is an arithmetic number, because the mean of its divisors is an integer number (2286633603).

Almost surely, 2^639765967680 is an apocalyptic number.

639765967680 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639765967680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1344540558564).

639765967680 is an abundant number, since it is smaller than the sum of its proper divisors (2049315149448).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639765967680 is an equidigital number, since it uses as much as digits as its factorization.

639765967680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723 (or 691 counting only the distinct ones).

The product of its (nonzero) digits is 617258880, while the sum is 72.

The spelling of 639765967680 in words is "six hundred thirty-nine billion, seven hundred sixty-five million, nine hundred sixty-seven thousand, six hundred eighty".