1638486779904 has 768 divisors, whose sum is σ = 5508743385600. Its totient is φ = 477417701376.

The previous prime is 1638486779869. The next prime is 1638486779921. The reversal of 1638486779904 is 4099776848361.

1638486779904 is a `hidden beast` number, since 16 + 384 + 86 + 7 + 79 + 90 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1868285514 + ... + 1868286390.

It is an arithmetic number, because the mean of its divisors is an integer number (7172842950).

Almost surely, 2^{1638486779904} 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 1638486779904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2754371692800).

1638486779904 is an abundant number, since it is smaller than the sum of its proper divisors (3870256605696).

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

1638486779904 is a wasteful number, since it uses less digits than its factorization.

1638486779904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1057 (or 1031 counting only the distinct ones).

The product of its (nonzero) digits is 438939648, while the sum is 72.

The spelling of 1638486779904 in words is "one trillion, six hundred thirty-eight billion, four hundred eighty-six million, seven hundred seventy-nine thousand, nine hundred four".