1561985983 has 2 divisors, whose sum is σ = 1561985984. Its totient is φ = 1561985982.

The previous prime is 1561985981. The next prime is 1561986059. The reversal of 1561985983 is 3895891651.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1561985983 - 2¹ = 1561985981 is a prime.

It is a super-2 number, since 2×1561985983² = 4879600422176952578, which contains 22 as substring.

Together with 1561985981, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561985981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780992991 + 780992992.

It is an arithmetic number, because the mean of its divisors is an integer number (780992992).

Almost surely, 2^1561985983 is an apocalyptic number.

1561985983 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561985983 is an equidigital number, since it uses as much as digits as its factorization.

1561985983 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2332800, while the sum is 55.

The square root of 1561985983 is about 39521.9683593821. The cubic root of 1561985983 is about 1160.2699488170.

The spelling of 1561985983 in words is "one billion, five hundred sixty-one million, nine hundred eighty-five thousand, nine hundred eighty-three".