1287721073 has 2 divisors, whose sum is σ = 1287721074. Its totient is φ = 1287721072.

The previous prime is 1287721069. The next prime is 1287721103. The reversal of 1287721073 is 3701277821.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1284003889 + 3717184 = 35833^2 + 1928^2 .

It is an emirp because it is prime and its reverse (3701277821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1287721073 - 2² = 1287721069 is a prime.

It is not a weakly prime, because it can be changed into another prime (1287721003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 643860536 + 643860537.

It is an arithmetic number, because the mean of its divisors is an integer number (643860537).

Almost surely, 2^1287721073 is an apocalyptic number.

It is an amenable number.

1287721073 is a deficient number, since it is larger than the sum of its proper divisors (1).

1287721073 is an equidigital number, since it uses as much as digits as its factorization.

1287721073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32928, while the sum is 38.

The square root of 1287721073 is about 35884.8306809437. The cubic root of 1287721073 is about 1087.9458192026.

Adding to 1287721073 its reverse (3701277821), we get a palindrome (4988998894).

The spelling of 1287721073 in words is "one billion, two hundred eighty-seven million, seven hundred twenty-one thousand, seventy-three".