6446399904 has 480 divisors, whose sum is σ = 22816797696. Its totient is φ = 1746800640.

The previous prime is 6446399903. The next prime is 6446399909. The reversal of 6446399904 is 4099936446.

6446399904 is a `hidden beast` number, since 6 + 4 + 463 + 99 + 90 + 4 = 666.

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 (6446399903) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 41059794 + ... + 41059950.

Almost surely, 2^6446399904 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 6446399904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11408398848).

6446399904 is an abundant number, since it is smaller than the sum of its proper divisors (16370397792).

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

6446399904 is a wasteful number, since it uses less digits than its factorization.

6446399904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 5038848, while the sum is 54.

The square root of 6446399904 is about 80289.4756739636. The cubic root of 6446399904 is about 1861.1115936094. Note that the first 3 decimals are identical.

The spelling of 6446399904 in words is "six billion, four hundred forty-six million, three hundred ninety-nine thousand, nine hundred four".