1388257920 has 512 divisors, whose sum is σ = 5875200000. Its totient is φ = 302911488.

The previous prime is 1388257891. The next prime is 1388257921. The reversal of 1388257920 is 297528831.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (1388257921) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 2781831 + ... + 2782329.

It is an arithmetic number, because the mean of its divisors is an integer number (11475000).

Almost surely, 2^1388257920 is an apocalyptic number.

1388257920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1388257920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2937600000).

1388257920 is an abundant number, since it is smaller than the sum of its proper divisors (4486942080).

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

1388257920 is a wasteful number, since it uses less digits than its factorization.

1388257920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557 (or 539 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The square root of 1388257920 is about 37259.3333273691. Note that the first 4 decimals coincide. The cubic root of 1388257920 is about 1115.5526013324.

The spelling of 1388257920 in words is "one billion, three hundred eighty-eight million, two hundred fifty-seven thousand, nine hundred twenty".