1287605820 has 48 divisors (see below), whose sum is σ = 3693237408. Its totient is φ = 334986240.

The previous prime is 1287605783. The next prime is 1287605867. The reversal of 1287605820 is 285067821.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 259249 + ... + 264168.

It is an arithmetic number, because the mean of its divisors is an integer number (76942446).

Almost surely, 2^1287605820 is an apocalyptic number.

1287605820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1287605820 is an abundant number, since it is smaller than the sum of its proper divisors (2405631588).

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

1287605820 is a wasteful number, since it uses less digits than its factorization.

1287605820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523470 (or 523468 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 39.

The square root of 1287605820 is about 35883.2247714723. The cubic root of 1287605820 is about 1087.9133606309.

The spelling of 1287605820 in words is "one billion, two hundred eighty-seven million, six hundred five thousand, eight hundred twenty".