1388969778 has 96 divisors (see below), whose sum is σ = 3304540800. Its totient is φ = 387991296.

The previous prime is 1388969753. The next prime is 1388969779. The reversal of 1388969778 is 8779698831.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1388969779) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2851851 + ... + 2852337.

It is an arithmetic number, because the mean of its divisors is an integer number (34422300).

Almost surely, 2^1388969778 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1388969778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1652270400).

1388969778 is an abundant number, since it is smaller than the sum of its proper divisors (1915571022).

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

1388969778 is a wasteful number, since it uses less digits than its factorization.

1388969778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 704 (or 697 counting only the distinct ones).

The product of its digits is 36578304, while the sum is 66.

The square root of 1388969778 is about 37268.8848505023. The cubic root of 1388969778 is about 1115.7432429843.

The spelling of 1388969778 in words is "one billion, three hundred eighty-eight million, nine hundred sixty-nine thousand, seven hundred seventy-eight".