639967910400 has 4320 divisors, whose sum is σ = 3316225872960. Its totient is φ = 120394874880.

The previous prime is 639967910399. The next prime is 639967910459. The reversal of 639967910400 is 4019769936.

639967910400 is a `hidden beast` number, since 6 + 3 + 99 + 67 + 91 + 0 + 400 = 666.

It is a tau number, because it is divible by the number of its divisors (4320).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 33682521591 + ... + 33682521609.

It is an arithmetic number, because the mean of its divisors is an integer number (767644878).

Almost surely, 2^639967910400 is an apocalyptic number.

639967910400 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 639967910400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1658112936480).

639967910400 is an abundant number, since it is smaller than the sum of its proper divisors (2676257962560).

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

639967910400 is a wasteful number, since it uses less digits than its factorization.

639967910400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106 (or 66 counting only the distinct ones).

The product of its (nonzero) digits is 2204496, while the sum is 54.

The spelling of 639967910400 in words is "six hundred thirty-nine billion, nine hundred sixty-seven million, nine hundred ten thousand, four hundred".