1287778 has 4 divisors (see below), whose sum is σ = 1931670. Its totient is φ = 643888.

The previous prime is 1287761. The next prime is 1287787. The reversal of 1287778 is 8777821.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 966289 + 321489 = 983^2 + 567^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 1287778.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321943 + ... + 321946.

2^1287778 is an apocalyptic number.

1287778 is a deficient number, since it is larger than the sum of its proper divisors (643892).

1287778 is an equidigital number, since it uses as much as digits as its factorization.

1287778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643891.

The product of its digits is 43904, while the sum is 40.

The square root of 1287778 is about 1134.8030666155. The cubic root of 1287778 is about 108.7961850775.

The spelling of 1287778 in words is "one million, two hundred eighty-seven thousand, seven hundred seventy-eight".