399781861632 has 576 divisors, whose sum is σ = 1288485273600. Its totient is φ = 121788334080.

The previous prime is 399781861631. The next prime is 399781861637. The reversal of 399781861632 is 236168187993.

399781861632 is a `hidden beast` number, since 3 + 9 + 9 + 7 + 8 + 1 + 8 + 616 + 3 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is a self number, because there is not a number n which added to its sum of digits gives 399781861632.

It is not an unprimeable number, because it can be changed into a prime (399781861631) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1054833219 + ... + 1054833597.

It is an arithmetic number, because the mean of its divisors is an integer number (2236953600).

Almost surely, 2^399781861632 is an apocalyptic number.

399781861632 is a gapful number since it is divisible by the number (32) 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 399781861632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (644242636800).

399781861632 is an abundant number, since it is smaller than the sum of its proper divisors (888703411968).

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

399781861632 is a wasteful number, since it uses less digits than its factorization.

399781861632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 659 (or 639 counting only the distinct ones).

The product of its digits is 23514624, while the sum is 63.

The spelling of 399781861632 in words is "three hundred ninety-nine billion, seven hundred eighty-one million, eight hundred sixty-one thousand, six hundred thirty-two".