1388921768 has 72 divisors (see below), whose sum is σ = 2916589950. Its totient is φ = 619781760.

The previous prime is 1388921741. The next prime is 1388921789. The reversal of 1388921768 is 8671298831.

It can be written as a sum of positive squares in 3 ways, for example, as 674856484 + 714065284 = 25978^2 + 26722^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1298738 + ... + 1299806.

Almost surely, 2^1388921768 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 1388921768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1458294975).

1388921768 is an abundant number, since it is smaller than the sum of its proper divisors (1527668182).

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

1388921768 is a wasteful number, since it uses less digits than its factorization.

1388921768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1163 (or 1115 counting only the distinct ones).

The product of its digits is 1161216, while the sum is 53.

The square root of 1388921768 is about 37268.2407419508. The cubic root of 1388921768 is about 1115.7303875449.

The spelling of 1388921768 in words is "one billion, three hundred eighty-eight million, nine hundred twenty-one thousand, seven hundred sixty-eight".