1561217087 has 2 divisors, whose sum is σ = 1561217088. Its totient is φ = 1561217086.

The previous prime is 1561217051. The next prime is 1561217107. The reversal of 1561217087 is 7807121651.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1561217087 - 2⁸ = 1561216831 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1561217087.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561217387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780608543 + 780608544.

It is an arithmetic number, because the mean of its divisors is an integer number (780608544).

Almost surely, 2^1561217087 is an apocalyptic number.

1561217087 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561217087 is an equidigital number, since it uses as much as digits as its factorization.

1561217087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23520, while the sum is 38.

The square root of 1561217087 is about 39512.2397112591. The cubic root of 1561217087 is about 1160.0795345288.

The spelling of 1561217087 in words is "one billion, five hundred sixty-one million, two hundred seventeen thousand, eighty-seven".