1287705638 has 8 divisors (see below), whose sum is σ = 1932831288. Its totient is φ = 643428544.

The previous prime is 1287705637. The next prime is 1287705659. The reversal of 1287705638 is 8365077821.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 1287705592 and 1287705601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1287705637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 208331 + ... + 214422.

It is an arithmetic number, because the mean of its divisors is an integer number (241603911).

Almost surely, 2^1287705638 is an apocalyptic number.

1287705638 is a deficient number, since it is larger than the sum of its proper divisors (645125650).

1287705638 is a wasteful number, since it uses less digits than its factorization.

1287705638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 424278.

The product of its (nonzero) digits is 564480, while the sum is 47.

The square root of 1287705638 is about 35884.6156172809. The cubic root of 1287705638 is about 1087.9414723734.

The spelling of 1287705638 in words is "one billion, two hundred eighty-seven million, seven hundred five thousand, six hundred thirty-eight".