1397840 has 40 divisors (see below), whose sum is σ = 3301128. Its totient is φ = 550400.

The previous prime is 1397839. The next prime is 1397857. The reversal of 1397840 is 487931.

It can be written as a sum of positive squares in 4 ways, for example, as 795664 + 602176 = 892^2 + 776^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 1397797 and 1397806.

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, 7994 + ... + 8166.

2^1397840 is an apocalyptic number.

1397840 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 1397840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1650564).

1397840 is an abundant number, since it is smaller than the sum of its proper divisors (1903288).

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

1397840 is a wasteful number, since it uses less digits than its factorization.

1397840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 1397840 is about 1182.3028376858. The cubic root of 1397840 is about 111.8113320204.

Subtracting from 1397840 its reverse (487931), we obtain a palindrome (909909).

The spelling of 1397840 in words is "one million, three hundred ninety-seven thousand, eight hundred forty".