1643219978400 has 4320 divisors, whose sum is σ = 8448284275200. Its totient is φ = 308477030400.

The previous prime is 1643219978339. The next prime is 1643219978509. The reversal of 1643219978400 is 48799123461.

1643219978400 is a `hidden beast` number, since 1 + 6 + 43 + 2 + 199 + 7 + 8 + 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 (19) of ones.

It is a polite number, since it can be written in 719 ways as a sum of consecutive naturals, for example, 34962127177 + ... + 34962127223.

It is an arithmetic number, because the mean of its divisors is an integer number (1955621360).

Almost surely, 2^{1643219978400} is an apocalyptic number.

1643219978400 is a gapful number since it is divisible by the number (10) 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 1643219978400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4224142137600).

1643219978400 is an abundant number, since it is smaller than the sum of its proper divisors (6805064296800).

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

1643219978400 is a wasteful number, since it uses less digits than its factorization.

1643219978400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135 (or 88 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 54.

The spelling of 1643219978400 in words is "one trillion, six hundred forty-three billion, two hundred nineteen million, nine hundred seventy-eight thousand, four hundred".