1217561987 has 2 divisors, whose sum is σ = 1217561988. Its totient is φ = 1217561986.

The previous prime is 1217561977. The next prime is 1217562001. The reversal of 1217561987 is 7891657121.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1217561987 - 2⁸ = 1217561731 is a prime.

It is not a weakly prime, because it can be changed into another prime (1217561977) 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, 608780993 + 608780994.

It is an arithmetic number, because the mean of its divisors is an integer number (608780994).

Almost surely, 2^1217561987 is an apocalyptic number.

1217561987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1217561987 is an equidigital number, since it uses as much as digits as its factorization.

1217561987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 211680, while the sum is 47.

The square root of 1217561987 is about 34893.5808853147. The cubic root of 1217561987 is about 1067.8174824401.

The spelling of 1217561987 in words is "one billion, two hundred seventeen million, five hundred sixty-one thousand, nine hundred eighty-seven".