1388640 has 96 divisors (see below), whose sum is σ = 4790016. Its totient is φ = 335360.

The previous prime is 1388633. The next prime is 1388641. The reversal of 1388640 is 468831.

1388640 = T₅₅₁ + T₅₅₂ + ... + T₅₅₉.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1388598 and 1388607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1388641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5149 + ... + 5411.

It is an arithmetic number, because the mean of its divisors is an integer number (49896).

2^1388640 is an apocalyptic number.

1388640 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 1388640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2395008).

1388640 is an abundant number, since it is smaller than the sum of its proper divisors (3401376).

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

1388640 is a wasteful number, since it uses less digits than its factorization.

1388640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 1388640 is about 1178.4057026339. The cubic root of 1388640 is about 111.5654933720.

It can be divided in two parts, 138 and 8640, that added together give a palindrome (8778).

The spelling of 1388640 in words is "one million, three hundred eighty-eight thousand, six hundred forty".