1328638907556 has 45 divisors (see below), whose sum is σ = 3473378791729. Its totient is φ = 442872719856.

The previous prime is 1328638907543. The next prime is 1328638907573. The reversal of 1328638907556 is 6557098368231.

The square root of 1328638907556 is 1152666.

It is a perfect power (a square), and thus also a powerful number.

1328638907556 is a `hidden beast` number, since 13 + 2 + 8 + 63 + 8 + 9 + 0 + 7 + 556 = 666.

It can be written as a sum of positive squares in only one way, i.e., 25808422500 + 1302830485056 = 160650^2 + 1141416^2 .

It is a super-2 number, since 2×1328638907556² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1328638907493 and 1328638907502.

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 20715970 + ... + 20780006.

Almost surely, 2^{1328638907556} is an apocalyptic number.

1328638907556 is the 1152666-th square number.

It is an amenable number.

1328638907556 is an abundant number, since it is smaller than the sum of its proper divisors (2144739884173).

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

1328638907556 is an frugal number, since it uses more digits than its factorization.

1328638907556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128090 (or 64042 counting only the distinct ones).

The product of its (nonzero) digits is 65318400, while the sum is 63.

The spelling of 1328638907556 in words is "one trillion, three hundred twenty-eight billion, six hundred thirty-eight million, nine hundred seven thousand, five hundred fifty-six".