1661815783 has 2 divisors, whose sum is σ = 1661815784. Its totient is φ = 1661815782.

The previous prime is 1661815777. The next prime is 1661815861. The reversal of 1661815783 is 3875181661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1661815783 - 2¹³ = 1661807591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661815763) 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, 830907891 + 830907892.

It is an arithmetic number, because the mean of its divisors is an integer number (830907892).

Almost surely, 2^1661815783 is an apocalyptic number.

1661815783 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661815783 is an equidigital number, since it uses as much as digits as its factorization.

1661815783 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 46.

The square root of 1661815783 is about 40765.3748050965. The cubic root of 1661815783 is about 1184.4797120129.

The spelling of 1661815783 in words is "one billion, six hundred sixty-one million, eight hundred fifteen thousand, seven hundred eighty-three".