1561993513 has 2 divisors, whose sum is σ = 1561993514. Its totient is φ = 1561993512.

The previous prime is 1561993493. The next prime is 1561993547. The reversal of 1561993513 is 3153991651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 964288809 + 597704704 = 31053^2 + 24448^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1561993513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1561993513.

It is not a weakly prime, because it can be changed into another prime (1561993913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780996756 + 780996757.

It is an arithmetic number, because the mean of its divisors is an integer number (780996757).

Almost surely, 2^1561993513 is an apocalyptic number.

It is an amenable number.

1561993513 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561993513 is an equidigital number, since it uses as much as digits as its factorization.

1561993513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 109350, while the sum is 43.

The square root of 1561993513 is about 39522.0636227412. The cubic root of 1561993513 is about 1160.2718132850.

The spelling of 1561993513 in words is "one billion, five hundred sixty-one million, nine hundred ninety-three thousand, five hundred thirteen".