639974121780 has 96 divisors (see below), whose sum is σ = 2056860368640. Its totient is φ = 145641000960.

The previous prime is 639974121769. The next prime is 639974121781. The reversal of 639974121780 is 87121479936.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 639974121780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639974121781) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3230781 + ... + 3423140.

It is an arithmetic number, because the mean of its divisors is an integer number (21425628840).

Almost surely, 2^639974121780 is an apocalyptic number.

639974121780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

639974121780 is an abundant number, since it is smaller than the sum of its proper divisors (1416886246860).

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

639974121780 is a wasteful number, since it uses less digits than its factorization.

639974121780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6654169 (or 6654167 counting only the distinct ones).

The product of its (nonzero) digits is 4572288, while the sum is 57.

The spelling of 639974121780 in words is "six hundred thirty-nine billion, nine hundred seventy-four million, one hundred twenty-one thousand, seven hundred eighty".