1561688503 has 4 divisors (see below), whose sum is σ = 1565246320. Its totient is φ = 1558130688.

The previous prime is 1561688467. The next prime is 1561688507. The reversal of 1561688503 is 3058861651.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1561688503 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561688503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561688507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1778250 + ... + 1779127.

It is an arithmetic number, because the mean of its divisors is an integer number (391311580).

Almost surely, 2^1561688503 is an apocalyptic number.

1561688503 is a deficient number, since it is larger than the sum of its proper divisors (3557817).

1561688503 is an equidigital number, since it uses as much as digits as its factorization.

1561688503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3557816.

The product of its (nonzero) digits is 172800, while the sum is 43.

The square root of 1561688503 is about 39518.2047036553. The cubic root of 1561688503 is about 1160.1962863936.

The spelling of 1561688503 in words is "one billion, five hundred sixty-one million, six hundred eighty-eight thousand, five hundred three".