1405840 has 20 divisors (see below), whose sum is σ = 3268764. Its totient is φ = 562304.

The previous prime is 1405823. The next prime is 1405841. The reversal of 1405840 is 485041.

It can be written as a sum of positive squares in 2 ways, for example, as 746496 + 659344 = 864^2 + 812^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×1405840² = 3952772211200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1405841) 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, 8707 + ... + 8866.

2^1405840 is an apocalyptic number.

1405840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1405840 is an abundant number, since it is smaller than the sum of its proper divisors (1862924).

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

1405840 is a wasteful number, since it uses less digits than its factorization.

1405840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17586 (or 17580 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 1405840 is about 1185.6812387822. The cubic root of 1405840 is about 112.0242294518.

The spelling of 1405840 in words is "one million, four hundred five thousand, eight hundred forty".