399820861440 has 1872 divisors, whose sum is σ = 1884370872384. Its totient is φ = 76299632640.

The previous prime is 399820861439. The next prime is 399820861457. The reversal of 399820861440 is 44168028993.

399820861440 is a `hidden beast` number, since 39 + 98 + 2 + 0 + 86 + 1 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (1872).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 2029547422 + ... + 2029547618.

It is an arithmetic number, because the mean of its divisors is an integer number (1006608372).

Almost surely, 2^399820861440 is an apocalyptic number.

399820861440 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 399820861440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (942185436192).

399820861440 is an abundant number, since it is smaller than the sum of its proper divisors (1484550010944).

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

399820861440 is a wasteful number, since it uses less digits than its factorization.

399820861440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274 (or 238 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 54.

The spelling of 399820861440 in words is "three hundred ninety-nine billion, eight hundred twenty million, eight hundred sixty-one thousand, four hundred forty".