1387840 has 28 divisors (see below), whose sum is σ = 3305556. Its totient is φ = 555008.

The previous prime is 1387823. The next prime is 1387847. The reversal of 1387840 is 487831.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 186624 + 1201216 = 432^2 + 1096^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1387847) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1849 + ... + 2488.

2^1387840 is an apocalyptic number.

1387840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1387840 is an abundant number, since it is smaller than the sum of its proper divisors (1917716).

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

1387840 is an equidigital number, since it uses as much as digits as its factorization.

1387840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4354 (or 4344 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 1387840 is about 1178.0662120611. The cubic root of 1387840 is about 111.5440648424.

Subtracting from 1387840 its reverse (487831), we obtain a palindrome (900009).

The spelling of 1387840 in words is "one million, three hundred eighty-seven thousand, eight hundred forty".