1287665380 has 24 divisors (see below), whose sum is σ = 2706851448. Its totient is φ = 514541568.

The previous prime is 1287665317. The next prime is 1287665389. The reversal of 1287665380 is 835667821.

It can be written as a sum of positive squares in 4 ways, for example, as 450373284 + 837292096 = 21222^2 + 28936^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1287665380.

It is not an unprimeable number, because it can be changed into a prime (1287665389) by changing a digit.

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, 12349 + ... + 52228.

It is an arithmetic number, because the mean of its divisors is an integer number (112785477).

Almost surely, 2^1287665380 is an apocalyptic number.

1287665380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1287665380 is an abundant number, since it is smaller than the sum of its proper divisors (1419186068).

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

1287665380 is a wasteful number, since it uses less digits than its factorization.

1287665380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65583 (or 65581 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 46.

The square root of 1287665380 is about 35884.0546761371. The cubic root of 1287665380 is about 1087.9301346880.

The spelling of 1287665380 in words is "one billion, two hundred eighty-seven million, six hundred sixty-five thousand, three hundred eighty".