6399121193920 has 1344 divisors, whose sum is σ = 21183227412480. Its totient is φ = 1816451481600.

The previous prime is 6399121193879. The next prime is 6399121193923. The reversal of 6399121193920 is 293911219936.

It is a super-2 number, since 2×6399121193920² (a number of 26 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6399121193923) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 7627080861 + ... + 7627081699.

It is an arithmetic number, because the mean of its divisors is an integer number (15761329920).

Almost surely, 2^{6399121193920} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6399121193920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10591613706240).

6399121193920 is an abundant number, since it is smaller than the sum of its proper divisors (14784106218560).

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

6399121193920 is a wasteful number, since it uses less digits than its factorization.

6399121193920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1002 (or 985 counting only the distinct ones).

The product of its (nonzero) digits is 1417176, while the sum is 55.

The spelling of 6399121193920 in words is "six trillion, three hundred ninety-nine billion, one hundred twenty-one million, one hundred ninety-three thousand, nine hundred twenty".