1287840 has 48 divisors (see below), whose sum is σ = 4058208. Its totient is φ = 343296.

The previous prime is 1287829. The next prime is 1287841. The reversal of 1287840 is 487821.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-3 number, since 3×1287840³ = 6407771033382912000, which contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1287798 and 1287807.

It is not an unprimeable number, because it can be changed into a prime (1287841) 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, 862 + ... + 1821.

It is an arithmetic number, because the mean of its divisors is an integer number (84546).

2^1287840 is an apocalyptic number.

1287840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1287840 is an abundant number, since it is smaller than the sum of its proper divisors (2770368).

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

1287840 is a wasteful number, since it uses less digits than its factorization.

1287840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2701 (or 2693 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 1287840 is about 1134.8303838019. The cubic root of 1287840 is about 108.7979310449.

The spelling of 1287840 in words is "one million, two hundred eighty-seven thousand, eight hundred forty".