1661165977 has 2 divisors, whose sum is σ = 1661165978. Its totient is φ = 1661165976.

The previous prime is 1661165971. The next prime is 1661166019. The reversal of 1661165977 is 7795611661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1112622736 + 548543241 = 33356^2 + 23421^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661165977 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1661165977.

It is not a weakly prime, because it can be changed into another prime (1661165971) 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, 830582988 + 830582989.

It is an arithmetic number, because the mean of its divisors is an integer number (830582989).

Almost surely, 2^1661165977 is an apocalyptic number.

It is an amenable number.

1661165977 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661165977 is an equidigital number, since it uses as much as digits as its factorization.

1661165977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 476280, while the sum is 49.

The square root of 1661165977 is about 40757.4039531470. The cubic root of 1661165977 is about 1184.3253061366.

The spelling of 1661165977 in words is "one billion, six hundred sixty-one million, one hundred sixty-five thousand, nine hundred seventy-seven".