1287228662721 has 27 divisors (see below), whose sum is σ = 1865501139619. Its totient is φ = 855313770192.

The previous prime is 1287228662711. The next prime is 1287228662729. The reversal of 1287228662721 is 1272668227821.

It is a happy number.

The square root of 1287228662721 is 1134561.

It is a perfect power (a square), and thus also a powerful number.

1287228662721 is a `hidden beast` number, since 1 + 2 + 8 + 7 + 2 + 2 + 8 + 6 + 627 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1046756118321 + 240472544400 = 1023111^2 + 490380^2 .

It is not a de Polignac number, because 1287228662721 - 2²³ = 1287220274113 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1287228662729) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1732474276 + ... + 1732475018.

Almost surely, 2^{1287228662721} is an apocalyptic number.

1287228662721 is the 1134561-st square number.

1287228662721 is the 567281-st centered octagonal number.

It is an amenable number.

1287228662721 is a deficient number, since it is larger than the sum of its proper divisors (578272476898).

1287228662721 is an frugal number, since it uses more digits than its factorization.

1287228662721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2510 (or 1255 counting only the distinct ones).

The product of its digits is 3612672, while the sum is 54.

The spelling of 1287228662721 in words is "one trillion, two hundred eighty-seven billion, two hundred twenty-eight million, six hundred sixty-two thousand, seven hundred twenty-one".