3987217561 has 2 divisors, whose sum is σ = 3987217562. Its totient is φ = 3987217560.

The previous prime is 3987217547. The next prime is 3987217571. The reversal of 3987217561 is 1657127893.

It is a happy number.

3987217561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3875809536 + 111408025 = 62256^2 + 10555^2 .

It is an emirp because it is prime and its reverse (1657127893) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3987217561 is a prime.

It is not a weakly prime, because it can be changed into another prime (3987217541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1993608780 + 1993608781.

It is an arithmetic number, because the mean of its divisors is an integer number (1993608781).

Almost surely, 2^3987217561 is an apocalyptic number.

It is an amenable number.

3987217561 is a deficient number, since it is larger than the sum of its proper divisors (1).

3987217561 is an equidigital number, since it uses as much as digits as its factorization.

3987217561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 635040, while the sum is 49.

The square root of 3987217561 is about 63144.4182885550. The cubic root of 3987217561 is about 1585.7083428469.

The spelling of 3987217561 in words is "three billion, nine hundred eighty-seven million, two hundred seventeen thousand, five hundred sixty-one".