1561518487 has 2 divisors, whose sum is σ = 1561518488. Its totient is φ = 1561518486.

The previous prime is 1561518481. The next prime is 1561518533. The reversal of 1561518487 is 7848151651.

It is an a-pointer prime, because the next prime (1561518533) can be obtained adding 1561518487 to its sum of digits (46).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1561518487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561518481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780759243 + 780759244.

It is an arithmetic number, because the mean of its divisors is an integer number (780759244).

Almost surely, 2^1561518487 is an apocalyptic number.

1561518487 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561518487 is an equidigital number, since it uses as much as digits as its factorization.

1561518487 is an evil number, because the sum of its binary digits is even.

The product of its digits is 268800, while the sum is 46.

The square root of 1561518487 is about 39516.0535352406. The cubic root of 1561518487 is about 1160.1541825874.

The spelling of 1561518487 in words is "one billion, five hundred sixty-one million, five hundred eighteen thousand, four hundred eighty-seven".