3978197521920 has 640 divisors, whose sum is σ = 14926296084480. Its totient is φ = 1002733240320.

The previous prime is 3978197521873. The next prime is 3978197521943. The reversal of 3978197521920 is 291257918793.

3978197521920 is a `hidden beast` number, since 3 + 9 + 7 + 8 + 19 + 7 + 521 + 92 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 92115372 + ... + 92158548.

It is an arithmetic number, because the mean of its divisors is an integer number (23322337632).

Almost surely, 2^{3978197521920} is an apocalyptic number.

3978197521920 is a gapful number since it is divisible by the number (30) 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 3978197521920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7463148042240).

3978197521920 is an abundant number, since it is smaller than the sum of its proper divisors (10948098562560).

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

3978197521920 is a wasteful number, since it uses less digits than its factorization.

3978197521920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43283 (or 43261 counting only the distinct ones).

The product of its (nonzero) digits is 17146080, while the sum is 63.

The spelling of 3978197521920 in words is "three trillion, nine hundred seventy-eight billion, one hundred ninety-seven million, five hundred twenty-one thousand, nine hundred twenty".