399324781440 has 512 divisors, whose sum is σ = 1603244160000. Its totient is φ = 93120897024.

The previous prime is 399324781423. The next prime is 399324781447. The reversal of 399324781440 is 44187423993.

399324781440 is a `hidden beast` number, since 3 + 99 + 32 + 4 + 7 + 81 + 440 = 666.

399324781440 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399324781447) 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, 4221381 + ... + 4314939.

It is an arithmetic number, because the mean of its divisors is an integer number (3131336250).

Almost surely, 2^399324781440 is an apocalyptic number.

399324781440 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 399324781440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (801622080000).

399324781440 is an abundant number, since it is smaller than the sum of its proper divisors (1203919378560).

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

399324781440 is a wasteful number, since it uses less digits than its factorization.

399324781440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93619 (or 93601 counting only the distinct ones).

The product of its (nonzero) digits is 5225472, while the sum is 54.

The spelling of 399324781440 in words is "three hundred ninety-nine billion, three hundred twenty-four million, seven hundred eighty-one thousand, four hundred forty".