1638653856 has 48 divisors (see below), whose sum is σ = 4915963584. Its totient is φ = 468186624.

The previous prime is 1638653843. The next prime is 1638653857. The reversal of 1638653856 is 6583568361.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1638653799 and 1638653808.

It is not an unprimeable number, because it can be changed into a prime (1638653857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1218565 + ... + 1219908.

It is an arithmetic number, because the mean of its divisors is an integer number (102415908).

Almost surely, 2^1638653856 is an apocalyptic number.

1638653856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1638653856 is an abundant number, since it is smaller than the sum of its proper divisors (3277309728).

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

1638653856 is a wasteful number, since it uses less digits than its factorization.

1638653856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2438493 (or 2438485 counting only the distinct ones).

The product of its digits is 3110400, while the sum is 51.

The square root of 1638653856 is about 40480.2897222834. The cubic root of 1638653856 is about 1178.9509627162.

The spelling of 1638653856 in words is "one billion, six hundred thirty-eight million, six hundred fifty-three thousand, eight hundred fifty-six".