1381840 has 40 divisors (see below), whose sum is σ = 3356928. Its totient is φ = 528000.

The previous prime is 1381837. The next prime is 1381859. The reversal of 1381840 is 481831.

It is a tau number, because it is divible by the number of its divisors (40).

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1465 + ... + 2215.

2^1381840 is an apocalyptic number.

1381840 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 1381840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1678464).

1381840 is an abundant number, since it is smaller than the sum of its proper divisors (1975088).

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

1381840 is a wasteful number, since it uses less digits than its factorization.

1381840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 787 (or 781 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 1381840 is about 1175.5169075773. The cubic root of 1381840 is about 111.3830877891.

Subtracting from 1381840 its reverse (481831), we obtain a palindrome (900009).

The spelling of 1381840 in words is "one million, three hundred eighty-one thousand, eight hundred forty".