1285820 has 24 divisors (see below), whose sum is σ = 2721600. Its totient is φ = 510272.

The previous prime is 1285813. The next prime is 1285841. The reversal of 1285820 is 285821.

It is a self number, because there is not a number n which added to its sum of digits gives 1285820.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4646 + ... + 4914.

It is an arithmetic number, because the mean of its divisors is an integer number (113400).

2^1285820 is an apocalyptic number.

1285820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1285820 is an abundant number, since it is smaller than the sum of its proper divisors (1435780).

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

1285820 is a wasteful number, since it uses less digits than its factorization.

1285820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 517 (or 515 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 1285820 is about 1133.9400336878. The cubic root of 1285820 is about 108.7410174463.

Subtracting from 1285820 its reverse (285821), we obtain a palindrome (999999).

The spelling of 1285820 in words is "one million, two hundred eighty-five thousand, eight hundred twenty".