1287864 has 48 divisors (see below), whose sum is σ = 3606720. Its totient is φ = 414720.

The previous prime is 1287857. The next prime is 1287883. The reversal of 1287864 is 4687821.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1944 + ... + 2520.

It is an arithmetic number, because the mean of its divisors is an integer number (75140).

2^1287864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1287864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1803360).

1287864 is an abundant number, since it is smaller than the sum of its proper divisors (2318856).

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

1287864 is a wasteful number, since it uses less digits than its factorization.

1287864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 620 (or 613 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 1287864 is about 1134.8409580201. The cubic root of 1287864 is about 108.7986068882.

The spelling of 1287864 in words is "one million, two hundred eighty-seven thousand, eight hundred sixty-four".