1783191661 has 2 divisors, whose sum is σ = 1783191662. Its totient is φ = 1783191660.

The previous prime is 1783191649. The next prime is 1783191677. The reversal of 1783191661 is 1661913871.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1754772100 + 28419561 = 41890^2 + 5331^2 .

It is an emirp because it is prime and its reverse (1661913871) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1783191661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1783191611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 891595830 + 891595831.

It is an arithmetic number, because the mean of its divisors is an integer number (891595831).

Almost surely, 2^1783191661 is an apocalyptic number.

It is an amenable number.

1783191661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1783191661 is an equidigital number, since it uses as much as digits as its factorization.

1783191661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 43.

The square root of 1783191661 is about 42227.8540894514. The cubic root of 1783191661 is about 1212.6421922164.

The spelling of 1783191661 in words is "one billion, seven hundred eighty-three million, one hundred ninety-one thousand, six hundred sixty-one".