1399840 has 48 divisors (see below), whose sum is σ = 3566808. Its totient is φ = 516096.

The previous prime is 1399837. The next prime is 1399843. The reversal of 1399840 is 489931.

It is an interprime number because it is at equal distance from previous prime (1399837) and next prime (1399843).

It can be written as a sum of positive squares in 4 ways, for example, as 753424 + 646416 = 868^2 + 804^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1399796 and 1399805.

It is not an unprimeable number, because it can be changed into a prime (1399843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1744 + ... + 2416.

2^1399840 is an apocalyptic number.

1399840 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 1399840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1783404).

1399840 is an abundant number, since it is smaller than the sum of its proper divisors (2166968).

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

1399840 is a wasteful number, since it uses less digits than its factorization.

1399840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701 (or 693 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 1399840 is about 1183.1483423477. The cubic root of 1399840 is about 111.8646323736.

Subtracting from 1399840 its reverse (489931), we obtain a palindrome (909909).

The spelling of 1399840 in words is "one million, three hundred ninety-nine thousand, eight hundred forty".